What is meant by the term friendly number?

The term "friendly number" refers to a pair of numbers that share a special relationship based on their divisors. Specifically, two numbers are considered friendly if the sum of the proper divisors of each number equals the other number. This concept is closely related to amicable numbers, where each number in the pair sums to the other. Friendly numbers reflect a deeper connection in number theory and can be explored through their divisor functions.