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...for when you just need to know.

Don't spend another second wondering if that number is prime. Check it! Primes will give you a lightning quick verdict. If your integer is not prime, peruse the list of prime factors to see what it's really made of.

NEW feature: Up to the Minute Primes! Stay posted about the prime number nearest to your moment in time on every launch.

Stay tuned for more features to meet all of your prime number needs! Useful for students of number theory and anyone who loves prime numbers!

Primes: for when you just need to know.