PrimeTool: Primes & Factors

PrimeTool is a pocket number-theory toolkit for students, teachers, puzzle fans, and anyone curious about numbers. Four tools give exact answers to everyday prime questions. Check & Factorize • Test whether any whole number up to 10^18 is prime • See the full prime factorization with the division steps • Get the number of divisors, the divisor sum σ, and Euler's φ • Find out whether a number is perfect, abundant, or deficient, and browse all of its divisors Generate Primes • List every prime up to a limit you choose, as high as 1,000,000 • See how many primes were found and the largest one Find Primes • Previous and next prime around any number, with the prime gap • The n-th prime, for n up to 50,000,000 • Prime counting π(x) for x up to one billion • All primes in a range up to 10^12, with the count, twin prime pairs, and the largest gap Integer Math • GCD and LCM with the Euclidean algorithm steps and Bézout coefficients • Modular power a^b mod m for numbers up to 10^18 • Modular inverse with a check line, or the reason none exists Handy extras • Long calculations can be cancelled at any time • Copy or share any result in one tap • Save your inputs as named scenarios with notes and reload them later