PrimeTool: Primes & Factors

TipTinker

Contains adsIn-app purchases

About this app

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

What’s new

Performance improvements and bug fixes