No, 51 is not a prime number. It is a composite number: its digits add up to 6, which is divisible by 3, so 51 is divisible by 3.
51 has divisors other than 1 and itself. The smallest is 3: 51 ÷ 3 = 17.
Prime factorization: 51 = 3 × 17.
| Number | Prime? |
|---|---|
| 47 | Yes |
| 48 | No, 2 × 2 × 2 × 2 × 3 |
| 49 | No, 7 × 7 |
| 50 | No, 2 × 5 × 5 |
| 52 | No, 2 × 2 × 13 |
| 53 | Yes |
| 54 | No, 2 × 3 × 3 × 3 |
| 55 | No, 5 × 11 |
More about 51: factors of 51 · 51 squared · square root of 51 · 51 in binary · 51 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.