Yes, 199 is a prime number. Its only factors are 1 and 199.
A number is prime if no smaller prime up to its square root divides it. The square root of 199 is about 14.11, so it is enough to test the primes 2, 3, 5, 7, 11 and 13.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
| 3 | 1 | No |
| 5 | 4 | No |
| 7 | 3 | No |
| 11 | 1 | No |
| 13 | 4 | No |
None of them divides 199 evenly, so 199 is prime.
| Number | Prime? |
|---|---|
| 195 | No, 3 × 5 × 13 |
| 196 | No, 2 × 2 × 7 × 7 |
| 197 | Yes |
| 198 | No, 2 × 3 × 3 × 11 |
| 200 | No, 2 × 2 × 2 × 5 × 5 |
| 201 | No, 3 × 67 |
| 202 | No, 2 × 101 |
| 203 | No, 7 × 29 |
More about 199: factors of 199 · square root of 199 · 199 in binary.
Another number? Use the prime number checker for any value, or see the list of prime numbers.