Yes, 443 is a prime number. Its only factors are 1 and 443.
A number is prime if no smaller prime up to its square root divides it. The square root of 443 is about 21.05, so it is enough to test the primes 2, 3, 5, 7, 11, 13, 17 and 19.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
| 3 | 2 | No |
| 5 | 3 | No |
| 7 | 2 | No |
| 11 | 3 | No |
| 13 | 1 | No |
| 17 | 1 | No |
| 19 | 6 | No |
None of them divides 443 evenly, so 443 is prime.
| Number | Prime? |
|---|---|
| 439 | Yes |
| 440 | No, 2 × 2 × 2 × 5 × 11 |
| 441 | No, 3 × 3 × 7 × 7 |
| 442 | No, 2 × 13 × 17 |
| 444 | No, 2 × 2 × 3 × 37 |
| 445 | No, 5 × 89 |
| 446 | No, 2 × 223 |
| 447 | No, 3 × 149 |
Another number? Use the prime number checker for any value, or see the list of prime numbers.