Check any positive integer for primality. Supports prime checking, factorization, and prime range generation. All computation happens locally in your browser.
A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. Examples: 2, 3, 5, 7, 11.
1 is not considered prime because it has only one positive divisor (itself). Prime numbers must have exactly two distinct positive divisors.
The tool uses trial division with optimization up to the square root. It first checks divisibility by small primes, then tests numbers of the form 6k±1.
Prime factorization is fundamental in cryptography (RSA encryption), number theory, and finding GCD/LCM of numbers.