No, 309 is not a prime number. It is a composite number: its digits add up to 12, which is divisible by 3, so 309 is divisible by 3.
309 has divisors other than 1 and itself. The smallest is 3: 309 ÷ 3 = 103.
Prime factorization: 309 = 3 × 103.
| Number | Prime? |
|---|---|
| 305 | No, 5 × 61 |
| 306 | No, 2 × 3 × 3 × 17 |
| 307 | Yes |
| 308 | No, 2 × 2 × 7 × 11 |
| 310 | No, 2 × 5 × 31 |
| 311 | Yes |
| 312 | No, 2 × 2 × 2 × 3 × 13 |
| 313 | Yes |
Another number? Use the prime number checker for any value, or see the list of prime numbers.