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

Example Sentences

"Without the scientific study, it can’t be said what will be the perfect number for Mount Everest," he said.

From BBC

Still, Pi is not a perfect number.

From Seattle Times

“It’s one of those days, every shot you hit just has a perfect number,” An said.

From Seattle Times

For me Bob Latchford was the perfect number nine, his buccaneering style was suited to that era in the '70s and early '80s.

From BBC

"In light of the weekend's events, I don't think it could have been a more perfect number."

From Reuters