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Primes and Factors Calculator

Type in a number and
  * check if it is prime or
* show all its prime factors or
* show all factors (prime or not) or
* see if it is the the sum of two odd primes
For help, click on any word shown like this.

Number or range:
I will ask you if I estimate that a number
may take up to seconds to check if it is prime.

© Dr Ron Knott       20 September 2000

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Primes, Factors and Divisibility