Yes, 239 is a prime number. Its only factors are 1 and 239.
A number is prime if no smaller prime up to its square root divides it. The square root of 239 is about 15.46, so it is enough to test the primes 2, 3, 5, 7, 11 and 13.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
| 3 | 2 | No |
| 5 | 4 | No |
| 7 | 1 | No |
| 11 | 8 | No |
| 13 | 5 | No |
None of them divides 239 evenly, so 239 is prime.
| Number | Prime? |
|---|---|
| 235 | No, 5 × 47 |
| 236 | No, 2 × 2 × 59 |
| 237 | No, 3 × 79 |
| 238 | No, 2 × 7 × 17 |
| 240 | No, 2 × 2 × 2 × 2 × 3 × 5 |
| 241 | Yes |
| 242 | No, 2 × 11 × 11 |
| 243 | No, 3 × 3 × 3 × 3 × 3 |
More about 239: 239 in binary.
Another number? Use the prime number checker for any value, or see the list of prime numbers.