Yes, 89 is a prime number. Its only factors are 1 and 89.
A number is prime if no smaller prime up to its square root divides it. The square root of 89 is about 9.43, so it is enough to test the primes 2, 3, 5 and 7.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
| 3 | 2 | No |
| 5 | 4 | No |
| 7 | 5 | No |
None of them divides 89 evenly, so 89 is prime.
| Number | Prime? |
|---|---|
| 85 | No, 5 × 17 |
| 86 | No, 2 × 43 |
| 87 | No, 3 × 29 |
| 88 | No, 2 × 2 × 2 × 11 |
| 90 | No, 2 × 3 × 3 × 5 |
| 91 | No, 7 × 13 |
| 92 | No, 2 × 2 × 23 |
| 93 | No, 3 × 31 |
More about 89: factors of 89 · 89 squared · square root of 89 · 89 in binary · 89 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.