This App provides some tools to factor large numbers with your phone. In particular it provides you: - trial division - Pollard's Rho method - we are implementing Quadratic Sieve that will be available in near future
You can test strong pseudo-primality of a number and search the next strong pseudo-prime number; we plan to add some deterministic algorithm to check primality of these numbers.
If you need a number with big factors there is an utility to create it. Results can be shared as text where you prefer.