No, 55 is not a prime number. It is a composite number: it ends in 5, so it is divisible by 5.
55 has divisors other than 1 and itself. The smallest is 5: 55 ÷ 5 = 11.
Prime factorization: 55 = 5 × 11.
| Number | Prime? |
|---|---|
| 51 | No, 3 × 17 |
| 52 | No, 2 × 2 × 13 |
| 53 | Yes |
| 54 | No, 2 × 3 × 3 × 3 |
| 56 | No, 2 × 2 × 2 × 7 |
| 57 | No, 3 × 19 |
| 58 | No, 2 × 29 |
| 59 | Yes |
More about 55: factors of 55 · 55 squared · square root of 55 · 55 in binary · 55 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.