Calculate the prime numbers between two limits. It uses a deterministic test.

Calculate the factors of any number with a single click. 99¢ only.

Test any number for primality with a single click. 99¢

Software for exploring the Prime Number Spiral (a.k.a. the Ulam Spiral)

For factoring integers, finding primes and plotting associated histograms

Find the prime factors and closest primes of any integer up to one billion (US)