Yes, 5 is a prime number. Its only factors are 1 and 5.
A number is prime if no smaller prime up to its square root divides it. The square root of 5 is about 2.24, so it is enough to test the primes 2.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
None of them divides 5 evenly, so 5 is prime.
| Number | Prime? |
|---|---|
| 1 | No (neither) |
| 2 | Yes |
| 3 | Yes |
| 4 | No, 2 × 2 |
| 6 | No, 2 × 3 |
| 7 | Yes |
| 8 | No, 2 × 2 × 2 |
| 9 | No, 3 × 3 |
More about 5: factors of 5 · 5 squared · square root of 5 · 5 in binary · 5 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.