Yes, 103 is a prime number. Its only factors are 1 and 103.
A number is prime if no smaller prime up to its square root divides it. The square root of 103 is about 10.15, 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 | 3 | No |
| 7 | 5 | No |
None of them divides 103 evenly, so 103 is prime.
| Number | Prime? |
|---|---|
| 99 | No, 3 × 3 × 11 |
| 100 | No, 2 × 2 × 5 × 5 |
| 101 | Yes |
| 102 | No, 2 × 3 × 17 |
| 104 | No, 2 × 2 × 2 × 13 |
| 105 | No, 3 × 5 × 7 |
| 106 | No, 2 × 53 |
| 107 | Yes |
More about 103: factors of 103 · 103 squared · square root of 103 · 103 in binary · 103 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.