Yes, 197 is a prime number. Its only factors are 1 and 197.
A number is prime if no smaller prime up to its square root divides it. The square root of 197 is about 14.04, so it is enough to test the primes 2, 3, 5, 7, 11 and 13.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
| 3 | 2 | No |
| 5 | 2 | No |
| 7 | 1 | No |
| 11 | 10 | No |
| 13 | 2 | No |
None of them divides 197 evenly, so 197 is prime.
| Number | Prime? |
|---|---|
| 193 | Yes |
| 194 | No, 2 × 97 |
| 195 | No, 3 × 5 × 13 |
| 196 | No, 2 × 2 × 7 × 7 |
| 198 | No, 2 × 3 × 3 × 11 |
| 199 | Yes |
| 200 | No, 2 × 2 × 2 × 5 × 5 |
| 201 | No, 3 × 67 |
More about 197: factors of 197 · square root of 197 · 197 in binary.
Another number? Use the prime number checker for any value, or see the list of prime numbers.