Yes, 79 is a prime number. Its only factors are 1 and 79.
A number is prime if no smaller prime up to its square root divides it. The square root of 79 is about 8.89, so it is enough to test the primes 2, 3, 5 and 7.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
| 3 | 1 | No |
| 5 | 4 | No |
| 7 | 2 | No |
None of them divides 79 evenly, so 79 is prime.
| Number | Prime? |
|---|---|
| 75 | No, 3 × 5 × 5 |
| 76 | No, 2 × 2 × 19 |
| 77 | No, 7 × 11 |
| 78 | No, 2 × 3 × 13 |
| 80 | No, 2 × 2 × 2 × 2 × 5 |
| 81 | No, 3 × 3 × 3 × 3 |
| 82 | No, 2 × 41 |
| 83 | Yes |
More about 79: factors of 79 · 79 squared · square root of 79 · 79 in binary · 79 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.