How do I know if a number is prime?

A prime number has exactly two positive divisors: 1 and itself. This checker tests the integer and shows its factors.

No. The number 1 has only one positive divisor, so it is not prime.

Can this checker handle large integers?

It works well for everyday integer checks in the browser. Very large integers may take longer because the test still has to inspect possible divisors.

Prime Number Checker

Check whether an integer is prime, inspect its factors, and jump to the nearest prime numbers.

Enter an Integer

Status

Why

Positive Factors

Prime Factorization

Previous Prime

Next Prime

Quick Examples

`2` is the smallest prime number.
`97` is prime because its only positive divisors are `1` and `97`.
`100` is not prime because it is divisible by `2`, `4`, `5`, `10`, and more.

FAQ

How do I know if a number is prime? A prime number has exactly two positive divisors: `1` and itself.
Is 1 a prime number? No. `1` is not prime because it has only one positive divisor.
Can this checker handle large integers? Yes for normal browser use, though very large integers may take longer to evaluate.

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