Yes, 211 is a prime number. Its only factors are 1 and 211.
A number is prime if no smaller prime up to its square root divides it. The square root of 211 is about 14.53, so it is enough to test the primes 2, 3, 5, 7, 11 and 13.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
| 3 | 1 | No |
| 5 | 1 | No |
| 7 | 1 | No |
| 11 | 2 | No |
| 13 | 3 | No |
None of them divides 211 evenly, so 211 is prime.
| Number | Prime? |
|---|---|
| 207 | No, 3 × 3 × 23 |
| 208 | No, 2 × 2 × 2 × 2 × 13 |
| 209 | No, 11 × 19 |
| 210 | No, 2 × 3 × 5 × 7 |
| 212 | No, 2 × 2 × 53 |
| 213 | No, 3 × 71 |
| 214 | No, 2 × 107 |
| 215 | No, 5 × 43 |
More about 211: 211 in binary.
Another number? Use the prime number checker for any value, or see the list of prime numbers.