A prime number is a whole number greater than 1 with exactly two factors: 1 and itself. There are 25 primes below 100 and 168 below 1000. Tap a number for a yes/no answer with proof, or use the prime number checker for any number.
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97
101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499
503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997
Is 1 prime? · Is 2 prime? · Is 3 prime? · Is 4 prime? · Is 5 prime? · Is 6 prime? · Is 7 prime? · Is 8 prime? · Is 9 prime? · Is 10 prime? · Is 11 prime? · Is 12 prime? · Is 13 prime? · Is 14 prime? · Is 15 prime? · Is 16 prime? · Is 17 prime? · Is 18 prime? · Is 19 prime? · Is 20 prime? · Is 21 prime? · Is 22 prime? · Is 23 prime? · Is 24 prime? · Is 25 prime? · Is 26 prime? · Is 27 prime? · Is 28 prime? · Is 29 prime? · Is 30 prime? · Is 31 prime? · Is 32 prime? · Is 33 prime? · Is 34 prime? · Is 35 prime? · Is 36 prime? · Is 37 prime? · Is 38 prime? · Is 39 prime? · Is 40 prime? · Is 41 prime? · Is 42 prime? · Is 43 prime? · Is 44 prime? · Is 45 prime? · Is 46 prime? · Is 47 prime? · Is 48 prime? · Is 49 prime? · Is 50 prime? · Is 51 prime? · Is 52 prime? · Is 53 prime? · Is 54 prime? · Is 55 prime? · Is 56 prime? · Is 57 prime? · Is 58 prime? · Is 59 prime? · Is 60 prime? · Is 61 prime? · Is 62 prime? · Is 63 prime? · Is 64 prime? · Is 65 prime? · Is 66 prime? · Is 67 prime? · Is 68 prime? · Is 69 prime? · Is 70 prime? · Is 71 prime? · Is 72 prime? · Is 73 prime? · Is 74 prime? · Is 75 prime? · Is 76 prime? · Is 77 prime? · Is 78 prime? · Is 79 prime? · Is 80 prime? · Is 81 prime? · Is 82 prime? · Is 83 prime? · Is 84 prime? · Is 85 prime? · Is 86 prime? · Is 87 prime? · Is 88 prime? · Is 89 prime? · Is 90 prime? · Is 91 prime? · Is 92 prime? · Is 93 prime? · Is 94 prime? · Is 95 prime? · Is 96 prime? · Is 97 prime? · Is 98 prime? · Is 99 prime? · Is 100 prime?
Is 101 prime? · Is 102 prime? · Is 103 prime? · Is 104 prime? · Is 105 prime? · Is 106 prime? · Is 107 prime? · Is 108 prime? · Is 109 prime? · Is 110 prime? · Is 111 prime? · Is 112 prime? · Is 113 prime? · Is 114 prime? · Is 115 prime? · Is 116 prime? · Is 117 prime? · Is 118 prime? · Is 119 prime? · Is 120 prime? · Is 121 prime? · Is 122 prime? · Is 123 prime? · Is 124 prime? · Is 125 prime? · Is 126 prime? · Is 127 prime? · Is 128 prime? · Is 129 prime? · Is 130 prime? · Is 131 prime? · Is 132 prime? · Is 133 prime? · Is 134 prime? · Is 135 prime? · Is 136 prime? · Is 137 prime? · Is 138 prime? · Is 139 prime? · Is 140 prime? · Is 141 prime? · Is 142 prime? · Is 143 prime? · Is 144 prime? · Is 145 prime? · Is 146 prime? · Is 147 prime? · Is 148 prime? · Is 149 prime? · Is 150 prime? · Is 151 prime? · Is 152 prime? · Is 153 prime? · Is 154 prime? · Is 155 prime? · Is 156 prime? · Is 157 prime? · Is 158 prime? · Is 159 prime? · Is 160 prime? · Is 161 prime? · Is 162 prime? · Is 163 prime? · Is 164 prime? · Is 165 prime? · Is 166 prime? · Is 167 prime? · Is 168 prime? · Is 169 prime? · Is 170 prime? · Is 171 prime? · Is 172 prime? · Is 173 prime? · Is 174 prime? · Is 175 prime? · Is 176 prime? · Is 177 prime? · Is 178 prime? · Is 179 prime? · Is 180 prime? · Is 181 prime? · Is 182 prime? · Is 183 prime? · Is 184 prime? · Is 185 prime? · Is 186 prime? · Is 187 prime? · Is 188 prime? · Is 189 prime? · Is 190 prime? · Is 191 prime? · Is 192 prime? · Is 193 prime? · Is 194 prime? · Is 195 prime? · Is 196 prime? · Is 197 prime? · Is 198 prime? · Is 199 prime? · Is 200 prime? · Is 201 prime? · Is 202 prime? · Is 203 prime? · Is 204 prime? · Is 205 prime? · Is 206 prime? · Is 207 prime? · Is 208 prime? · Is 209 prime? · Is 210 prime? · Is 211 prime? · Is 212 prime? · Is 213 prime? · Is 214 prime? · Is 215 prime? · Is 216 prime? · Is 217 prime? · Is 218 prime? · Is 219 prime? · Is 220 prime? · Is 221 prime? · Is 222 prime? · Is 223 prime? · Is 224 prime? · Is 225 prime? · Is 226 prime? · Is 227 prime? · Is 228 prime? · Is 229 prime? · Is 230 prime? · Is 231 prime? · Is 232 prime? · Is 233 prime? · Is 234 prime? · Is 235 prime? · Is 236 prime? · Is 237 prime? · Is 238 prime? · Is 239 prime? · Is 240 prime? · Is 241 prime? · Is 242 prime? · Is 243 prime? · Is 244 prime? · Is 245 prime? · Is 246 prime? · Is 247 prime? · Is 248 prime? · Is 249 prime? · Is 250 prime? · Is 251 prime? · Is 252 prime? · Is 253 prime? · Is 254 prime? · Is 255 prime? · Is 256 prime? · Is 257 prime? · Is 258 prime? · Is 259 prime? · Is 260 prime? · Is 261 prime? · Is 262 prime? · Is 263 prime? · Is 264 prime? · Is 265 prime? · Is 266 prime? · Is 267 prime? · Is 268 prime? · Is 269 prime? · Is 270 prime? · Is 271 prime? · Is 272 prime? · Is 273 prime? · Is 274 prime? · Is 275 prime? · Is 276 prime? · Is 277 prime? · Is 278 prime? · Is 279 prime? · Is 280 prime? · Is 281 prime? · Is 282 prime? · Is 283 prime? · Is 284 prime? · Is 285 prime? · Is 286 prime? · Is 287 prime? · Is 288 prime? · Is 289 prime? · Is 290 prime? · Is 291 prime? · Is 292 prime? · Is 293 prime? · Is 294 prime? · Is 295 prime? · Is 296 prime? · Is 297 prime? · Is 298 prime? · Is 299 prime? · Is 300 prime? · Is 301 prime? · Is 302 prime? · Is 303 prime? · Is 304 prime? · Is 305 prime? · Is 306 prime? · Is 307 prime? · Is 308 prime? · Is 309 prime? · Is 310 prime? · Is 311 prime? · Is 312 prime? · Is 313 prime? · Is 314 prime? · Is 315 prime? · Is 316 prime? · Is 317 prime? · Is 318 prime? · Is 319 prime? · Is 320 prime? · Is 321 prime? · Is 322 prime? · Is 323 prime? · Is 324 prime? · Is 325 prime? · Is 326 prime? · Is 327 prime? · Is 328 prime? · Is 329 prime? · Is 330 prime? · Is 331 prime? · Is 332 prime? · Is 333 prime? · Is 334 prime? · Is 335 prime? · Is 336 prime? · Is 337 prime? · Is 338 prime? · Is 339 prime? · Is 340 prime? · Is 341 prime? · Is 342 prime? · Is 343 prime? · Is 344 prime? · Is 345 prime? · Is 346 prime? · Is 347 prime? · Is 348 prime? · Is 349 prime? · Is 350 prime? · Is 351 prime? · Is 352 prime? · Is 353 prime? · Is 354 prime? · Is 355 prime? · Is 356 prime? · Is 357 prime? · Is 358 prime? · Is 359 prime? · Is 360 prime? · Is 361 prime? · Is 362 prime? · Is 363 prime? · Is 364 prime? · Is 365 prime? · Is 366 prime? · Is 367 prime? · Is 368 prime? · Is 369 prime? · Is 370 prime? · Is 371 prime? · Is 372 prime? · Is 373 prime? · Is 374 prime? · Is 375 prime? · Is 376 prime? · Is 377 prime? · Is 378 prime? · Is 379 prime? · Is 380 prime? · Is 381 prime? · Is 382 prime? · Is 383 prime? · Is 384 prime? · Is 385 prime? · Is 386 prime? · Is 387 prime? · Is 388 prime? · Is 389 prime? · Is 390 prime? · Is 391 prime? · Is 392 prime? · Is 393 prime? · Is 394 prime? · Is 395 prime? · Is 396 prime? · Is 397 prime? · Is 398 prime? · Is 399 prime? · Is 400 prime? · Is 401 prime? · Is 402 prime? · Is 403 prime? · Is 404 prime? · Is 405 prime? · Is 406 prime? · Is 407 prime? · Is 408 prime? · Is 409 prime? · Is 410 prime? · Is 411 prime? · Is 412 prime? · Is 413 prime? · Is 414 prime? · Is 415 prime? · Is 416 prime? · Is 417 prime? · Is 418 prime? · Is 419 prime? · Is 420 prime? · Is 421 prime? · Is 422 prime? · Is 423 prime? · Is 424 prime? · Is 425 prime? · Is 426 prime? · Is 427 prime? · Is 428 prime? · Is 429 prime? · Is 430 prime? · Is 431 prime? · Is 432 prime? · Is 433 prime? · Is 434 prime? · Is 435 prime? · Is 436 prime? · Is 437 prime? · Is 438 prime? · Is 439 prime? · Is 440 prime? · Is 441 prime? · Is 442 prime? · Is 443 prime? · Is 444 prime? · Is 445 prime? · Is 446 prime? · Is 447 prime? · Is 448 prime? · Is 449 prime? · Is 450 prime? · Is 451 prime? · Is 452 prime? · Is 453 prime? · Is 454 prime? · Is 455 prime? · Is 456 prime? · Is 457 prime? · Is 458 prime? · Is 459 prime? · Is 460 prime? · Is 461 prime? · Is 462 prime? · Is 463 prime? · Is 464 prime? · Is 465 prime? · Is 466 prime? · Is 467 prime? · Is 468 prime? · Is 469 prime? · Is 470 prime? · Is 471 prime? · Is 472 prime? · Is 473 prime? · Is 474 prime? · Is 475 prime? · Is 476 prime? · Is 477 prime? · Is 478 prime? · Is 479 prime? · Is 480 prime? · Is 481 prime? · Is 482 prime? · Is 483 prime? · Is 484 prime? · Is 485 prime? · Is 486 prime? · Is 487 prime? · Is 488 prime? · Is 489 prime? · Is 490 prime? · Is 491 prime? · Is 492 prime? · Is 493 prime? · Is 494 prime? · Is 495 prime? · Is 496 prime? · Is 497 prime? · Is 498 prime? · Is 499 prime? · Is 500 prime?
Is 501 prime? · Is 511 prime? · Is 521 prime? · Is 539 prime? · Is 541 prime? · Is 561 prime? · Is 601 prime? · Is 611 prime? · Is 641 prime? · Is 701 prime? · Is 713 prime? · Is 721 prime? · Is 743 prime? · Is 771 prime? · Is 791 prime? · Is 801 prime? · Is 811 prime? · Is 821 prime? · Is 851 prime? · Is 871 prime? · Is 901 prime? · Is 911 prime? · Is 919 prime? · Is 949 prime? · Is 971 prime? · Is 991 prime? · Is 997 prime? · Is 1,000 prime? · Is 1,001 prime? · Is 1,009 prime? · Is 1,024 prime? · Is 1,049 prime? · Is 1,111 prime? · Is 1,201 prime? · Is 1,231 prime? · Is 1,297 prime? · Is 1,357 prime? · Is 1,459 prime? · Is 1,501 prime? · Is 1,601 prime? · Is 1,729 prime? · Is 1,801 prime? · Is 1,901 prime? · Is 1,999 prime? · Is 2,001 prime? · Is 2,003 prime? · Is 2,017 prime? · Is 2,020 prime? · Is 2,021 prime? · Is 2,023 prime? · Is 2,024 prime? · Is 2,025 prime? · Is 2,027 prime? · Is 2,029 prime? · Is 2,999 prime? · Is 3,001 prime? · Is 4,001 prime? · Is 5,003 prime? · Is 7,919 prime? · Is 9,973 prime? · Is 10,007 prime? · Is 65,537 prime?
Related: factors of numbers · squares and cubes · GCF and LCM calculator.