Yes, 71 is a prime number. Its only factors are 1 and 71.
A number is prime if no smaller prime up to its square root divides it. The square root of 71 is about 8.43, so it is enough to test the primes 2, 3, 5 and 7.
| Divide by | Remainder | Divides evenly? |
|---|---|---|
| 2 | 1 | No |
| 3 | 2 | No |
| 5 | 1 | No |
| 7 | 1 | No |
None of them divides 71 evenly, so 71 is prime.
| Number | Prime? |
|---|---|
| 67 | Yes |
| 68 | No, 2 × 2 × 17 |
| 69 | No, 3 × 23 |
| 70 | No, 2 × 5 × 7 |
| 72 | No, 2 × 2 × 2 × 3 × 3 |
| 73 | Yes |
| 74 | No, 2 × 37 |
| 75 | No, 3 × 5 × 5 |
More about 71: factors of 71 · 71 squared · square root of 71 · 71 in binary · 71 in Roman numerals.
Another number? Use the prime number checker for any value, or see the list of prime numbers.