These 2 numbers are an example of Amicable Pair ie., the sum of all possible divisors of a number in the pair, except the number itself is equal to the other number in the pair and vice versa.
In other words:
(220) = sum of {1,2,4,5,10,11,20,22,44,55,110} = (284)
(284) = sum{1,2,4,71,142} = (220).