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Kordu Tools

Prime Number Tools

Check if a number is prime, find its prime factorization, list primes in a range, or find the Nth prime number.

Enter any positive integer to test whether it is prime. Results include the nearest prime and smallest factor for composite numbers.

All calculations run in your browser. No data is sent to any server. Primality testing uses trial division up to the square root. Prime listing uses the sieve of Eratosthenes.

How to use

  1. 1

    Choose a mode

    Select Primality Test, Factorization, List Primes, or Nth Prime using the tabs.

  2. 2

    Enter a number

    Type a positive integer into the input field.

  3. 3

    View the result

    Results appear instantly. Factorization shows the full prime decomposition.

Frequently asked questions

How large a number can I test?
Primality testing works well up to about 10^15. Factorization is practical up to about 10^12.
What algorithm is used for primality?
Trial division up to the square root of the number for smaller values.
How does the prime listing work?
It uses the sieve of Eratosthenes to efficiently find all primes in a given range.
Is my data sent to a server?
No. All calculations run entirely in your browser.

A suite of prime number tools in one page. Test whether any number is

prime, decompose a number into its prime factors shown as a product of

powers, generate all primes within a range using the sieve of

Eratosthenes, or find the Nth prime. Results appear instantly and

factor trees are displayed step by step. All processing runs in your

browser.

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