No, 155 is not a prime number. It is a composite number: it ends in 5, so it is divisible by 5.
155 has divisors other than 1 and itself. The smallest is 5: 155 ÷ 5 = 31.
Prime factorization: 155 = 5 × 31.
| Number | Prime? |
|---|---|
| 151 | Yes |
| 152 | No, 2 × 2 × 2 × 19 |
| 153 | No, 3 × 3 × 17 |
| 154 | No, 2 × 7 × 11 |
| 156 | No, 2 × 2 × 3 × 13 |
| 157 | Yes |
| 158 | No, 2 × 79 |
| 159 | No, 3 × 53 |
More about 155: factors of 155 · square root of 155 · 155 in binary.
Another number? Use the prime number checker for any value, or see the list of prime numbers.