Yes, 3 is a prime number. Its only factors are 1 and 3.
A number is prime if no smaller prime up to its square root divides it. The square root of 3 is about 1.73, so it is enough to test no divisors at all.
None of them divides 3 evenly, so 3 is prime.
| Number | Prime? |
|---|---|
| 1 | No (neither) |
| 2 | Yes |
| 4 | No, 2 × 2 |
| 5 | Yes |
| 6 | No, 2 × 3 |
| 7 | Yes |
More about 3: factors of 3 · 3 squared · square root of 3 · 3 in binary · 3 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.