perfect number


: an integer (such as 6 or 28) the sum of whose integral factors including 1 but excluding itself is equal to itself

Word History

First Known Use

14th century, in the meaning defined above

Time Traveler
The first known use of perfect number was in the 14th century

Dictionary Entries Near perfect number

Cite this Entry

“Perfect number.” Dictionary, Merriam-Webster, Accessed 30 Nov. 2023.

Kids Definition

perfect number

: a whole number that is equal to the sum of all its divisors except itself
28 is a perfect number because it is the sum of 1 + 2 + 4 + 7 + 14

More from Merriam-Webster on perfect number

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