[Glossary](https://useratio.app/glossary) › Maths and statistics

# Prime number

A whole number greater than 1 that only divides by 1 and itself.

97 is prime. 91 looks prime and is not: it is 7 × 13. When a number is not prime, Ratio shows its factors.

## In Ratio

| You type | Ratio shows |
| --- | --- |
| `isprime(91)` | not prime: 7 × 13 |
| `isprime(97)` | prime |

## Related

[Syntax and examples](https://useratio.app/docs) · [All terms](https://useratio.app/glossary)

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Source: https://useratio.app/glossary/prime-number