Amicable numbers are two numbers that are friends in a special way. If you take all the proper divisors (numbers that divide evenly into another number, excluding the number itself) of each number and add them up, you will find that each number's divisors add up to the other number. The smallest pair of amicable numbers is 220 and 284. Other pairs of amicable numbers include (1184, 1210), (2620, 2924), (5020, 5564), (6232, 6368), (10744, 10856), (12285, 14595), (17296, 18416), (63020, 76084), and (66928, 66992).
Since the divisors of 220 add up to 284 and the divisors of 284 add up to 220, these two numbers are amicable.