21K School/ Calculators/ Prime Number Calculator

Prime Number Calculator

Check if a number is prime, find all prime factors, and list primes in a range.

Primality Test

FEATURE

Factorisation

METHOD

Range List

OUTPUT

Enter Values

Number to check

Range: From

Range: To

Result

Result—

Detail—

Notes—

Steps

How It Works

Enter any integer to check if it is prime.

Prime factorisation is shown for composite numbers.

Set a range to list all primes between two numbers.

Example

Is 97 prime?

Test divisors to √97 ≈ 9.8

No divisors found

∴ 97 is prime ✅

Try Next Pick Your Next Calculator

Explore our other calculators

Ready to help your child find their path?

Speak to a 21K School counsellor about which learning path fits your family.