perfect number

noun

Mathematics.

1. a positive number that is equal to the sum of all positive integers that are submultiples of it, as 6, which is equal to the sum of 1, 2, and 3.

perfect number

noun

1. an integer, such as 28, that is equal to the sum of all its possible factors, excluding itself

perfect number

1. A positive integer that equals the sum of all of its divisors other than itself. An example is 28, whose divisors (not counting itself) are 1, 2, 4, 7, and 14, which added together give 28.

Word History and Origins

Origin of perfect number¹

Middle English word dating back to 1350–1400