Coprime integers - Wikipedia, the free encyclopedia

In number theory, two integers a and b are said to be relatively prime, mutually prime, or coprime (also spelled co-prime)^[1] if the only positive integer that evenly divides both of them is 1. That is, the only common positive factor of the two numbers is 1. This is equivalent to their greatest common divisor being 1.^[2] The numerator and denominator of a reduced fraction are coprime. In addition to and the notation is sometimes used to indicate that a and b are relatively prime.^[3]

For example, 14 and 15 are coprime, being commonly divisible by only 1, but 14 and 21 are not, because they are both divisible by 7. The numbers 1 and −1 are coprime to every integer, and they are the only integers to be coprime with 0.

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