perfect number

noun

A number that is the sum of all of its divisors except itself.

“The factors of 6 are 1, 2, 3 and 6, and 1 + 2 + 3 = 6, so 6 is a perfect number.”

OriginLatin numerus perfectus ← Ancient Greek τέλειος →
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Meanings

nounperfect number (plural perfect numbers)

plural perfect numbers

  1. mathematicsA number that is the sum of all of its divisors except itself.

    The factors of 6 are 1, 2, 3 and 6, and 1 + 2 + 3 = 6, so 6 is a perfect number.

    1 more example

    The factors of 28 are 1, 2, 4, 7, 14 and 28, and 1 + 2 + 4 + 7 + 14 = 28, so 28 is a perfect number.

Origin

  1. Ancient Greekτέλειος
  2. Latinnumerus perfectus
  3. Englishperfect number

Calque of Latin numerus perfectus, with this use of perfectus itself a semantic loan from Ancient Greek τέλειος (téleios).

More words from Latin, Ancient Greek

Full word history & related roots →

Translations

Catalan nombre perfecte
  • nombre perfectea number that is the sum of all of its divisors except itself
Chinese Mandarin 完全數 /完全数
  • 完全數 /完全数 (wánquánshù)a number that is the sum of all of its divisors except itself
Dutch perfect getal
  • perfect getala number that is the sum of all of its divisors except itself
Finnish täydellinen luku
  • täydellinen lukua number that is the sum of all of its divisors except itself
French nombre parfait
  • nombre parfaita number that is the sum of all of its divisors except itself
German vollkommene Zahl, perfekte Zahl
  • vollkommene Zahla number that is the sum of all of its divisors except itself
  • perfekte Zahla number that is the sum of all of its divisors except itself
  • ideale Zahla number that is the sum of all of its divisors except itself
Icelandic fullkomin tala
  • fullkomin talaa number that is the sum of all of its divisors except itself
Italian numero perfetto
  • numero perfettoa number that is the sum of all of its divisors except itself
Japanese 完全数
  • 完全数 (kanzen-su)a number that is the sum of all of its divisors except itself
Korean 완전수
  • 완전수 (wanjeonsu)a number that is the sum of all of its divisors except itself
Latin numerus perfectus
  • numerus perfectusa number that is the sum of all of its divisors except itself
Norwegian Bokmål perfekt tall
  • perfekt talla number that is the sum of all of its divisors except itself
Polish liczba doskonała
  • liczba doskonałaa number that is the sum of all of its divisors except itself
Portuguese número perfeito
  • número perfeitoa number that is the sum of all of its divisors except itself
Romanian număr perfect
  • număr perfecta number that is the sum of all of its divisors except itself
Russian соверше́нное число́
  • соверше́нное число́ (soveršénnoje čisló)a number that is the sum of all of its divisors except itself
Slovak dokonalé číslo
  • dokonalé čísloa number that is the sum of all of its divisors except itself
Spanish número perfecto
  • número perfectoa number that is the sum of all of its divisors except itself
Swedish perfekt tal
  • perfekt tala number that is the sum of all of its divisors except itself
Tagalog himpit na bilang
  • himpit na bilanga number that is the sum of all of its divisors except itself
Turkish mükemmel sayı
  • mükemmel sayıa number that is the sum of all of its divisors except itself
Cite this entry
APA

perfect number. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/perfect%20number

MLA

“perfect number.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/perfect%20number. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “perfect number,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/perfect%20number.

Source: perfect number on Wiktionary, CC BY-SA 4.0.