No, 255 is not a prime number. It is a composite number: it ends in 5, so it is divisible by 5.
255 has divisors other than 1 and itself. The smallest is 3: 255 ÷ 3 = 85.
Prime factorization: 255 = 3 × 5 × 17.
| Number | Prime? |
|---|---|
| 251 | Yes |
| 252 | No, 2 × 2 × 3 × 3 × 7 |
| 253 | No, 11 × 23 |
| 254 | No, 2 × 127 |
| 256 | No, 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2 |
| 257 | Yes |
| 258 | No, 2 × 3 × 43 |
| 259 | No, 7 × 37 |
More about 255: 255 in binary.
Another number? Use the prime number checker for any value, or see the list of prime numbers.