Prime Numbers

Generate primes and factor numbers.

Prime numbers are whole numbers greater than 1 that can only be divided evenly by 1 and themselves. Use whichever tool below matches what you need: test one number, break a number into its prime factors, or list every prime under a limit.

Is it a prime number?

Tests a single whole number for primality.

Number to test

Results appear here.

Prime factors

Breaks a number down into the primes that multiply together to make it.

Number to factor

Results appear here.

List primes below a number

Lists every prime smaller than the number you enter, up to 200,000.

Upper limit

Results appear here.

Sync across devices

Optionally back up your puzzle texts to our cloud and sync them to your other devices. Your notes are end-to-end encrypted on this device before they leave it, so we can never read them. You need your username and passphrase to unlock them, on any device.

Username

Your geocaching name usually works as it is, spaces and symbols included.

3 characters or more
Starts with a letter or a number
Uses only letters, numbers, spaces and . - _ ' & * ! ? + ( ) ~ @ #

Passphrase

6 characters or more
An upper case and a lower case letter
A number or a symbol
Not an obvious choice like "password"

Confirm passphrase

Do not store passwords, financial details, or other sensitive data here. It is encrypted and we cannot read it, but you are responsible for what you store. Provided as is, with no warranty. If you lose both your passphrase and recovery key, the data cannot be recovered.

No notes yet. Click + New to create your first puzzle text.