Math, Science & Calculators · Free Tool
Prime Factorisation
Check whether a number is prime and break it into its prime factors — with divisor count and sum — computed with big-integer precision in your browser.
How it works
The number is divided by 2, then by each odd number in turn, up to its square root — every divisor found is a prime factor, and its multiplicity is counted. Whatever remains above 1 is itself a prime. All arithmetic uses JavaScript BigInt, so precision never breaks. The divisor count is the product of each exponent plus one; the divisor sum uses the geometric-series formula. Very large numbers whose smallest prime factor is huge may exceed a quick search — you’ll be told if so.