For example, 7 = 1 + 1 + 1 + 1 + 1 + 1 + 1.. There is one positive integer (up to 1) that is relatively prime to 1.
1 is the multiplicative identity,.. Although the number 1 used to be considered a prime number, it requires special treatment in so many definitions and applications involving primes greater than or equal to 2 that it is usually.