1.NounAny of a sequence of numbers having the property that the sum of the divisors of each, excluding itself, is equal to the next number in the sequence; in the case of the last number of the sequence, the sum of the divisors, excluding that number, is equal to the first number of the sequence.
"The numbers in the sequence <1264460, 1547860, 1727636, 1305184> are sociable numbers."