perfect number

== English == === Etymology === Calque of Latin numerus perfectus, with this use of perfectus itself a semantic loan from Ancient Greek τέλειος (téleios). === Pronunciation === === Noun === perfect number (plural perfect numbers) (number theory) A number that is the sum of all of its divisors except itself. ==== Derived terms ==== ==== Translations ==== === See also === abundant number amicable numbers deficient number Mersenne prime sociable numbers Perfect number on Wikipedia.Wikipedia