No, 405 is not a prime number. It is a composite number: it ends in 5, so it is divisible by 5.
405 has divisors other than 1 and itself. The smallest is 3: 405 ÷ 3 = 135.
Prime factorization: 405 = 3 × 3 × 3 × 3 × 5 = 3⁴ × 5.
| Number | Prime? |
|---|---|
| 401 | Yes |
| 402 | No, 2 × 3 × 67 |
| 403 | No, 13 × 31 |
| 404 | No, 2 × 2 × 101 |
| 406 | No, 2 × 7 × 29 |
| 407 | No, 11 × 37 |
| 408 | No, 2 × 2 × 2 × 3 × 17 |
| 409 | Yes |
Another number? Use the prime number checker for any value, or see the list of prime numbers.