Yes, 61 is a prime number. Its only factors are 1 and 61.
A number is prime if no smaller prime up to its square root divides it. The square root of 61 is about 7.81, 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 | 1 | No |
| 7 | 5 | No |
None of them divides 61 evenly, so 61 is prime.
| Number | Prime? |
|---|---|
| 57 | No, 3 × 19 |
| 58 | No, 2 × 29 |
| 59 | Yes |
| 60 | No, 2 × 2 × 3 × 5 |
| 62 | No, 2 × 31 |
| 63 | No, 3 × 3 × 7 |
| 64 | No, 2 × 2 × 2 × 2 × 2 × 2 |
| 65 | No, 5 × 13 |
More about 61: factors of 61 · 61 squared · square root of 61 · 61 in binary · 61 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.