what is coprime

Coprime integers are two integers that have no common factor other than 1. In other words, the only positive integer that is a divisor of both of them is 1. For example, 9 and 10 are coprime because their only common factor is 1. However, 21 and 24 are not coprime because they have common factors other than 1. A set of integers can also be called coprime if its elements share no common positive factor except 1. A stronger condition on a set of integers is pairwise coprime, which means that a and b are coprime for every pair (a, b) of different integers in the set. The number of integers coprime with a positive integer n, between 1 and n, is given by Eulers totient function, also known as Eulers phi function, φ(n). Co-prime numbers are also referred to as relatively prime numbers.