In the sense that the sum of the proper positive divisors of each, sum to the other.
Amicable numbers have a long history in magic and astrology, making love potions and talismans.
There is no formula or method known to list all of the amicable numbers, but formulas for certain special types have been discovered throughout the years. Euler then topped them both by adding a list of sixty-four new amicable pairs, however he made two errors. In 1909 one of his pairs was found to be not amicable, and in 1914 the same fate took a second pair. Now extensive computer searches have found all such numbers with 10 or fewer digits and numerous larger examples, for a total of over 7500 amicable pairs. It is unknown if there are infinitely many pairs of amicable numbers.