84 (eighty-four) is the natural number following 83 and preceding 85.

In mathematics

A hepteract is a seven-dimensional hypercube with 84 penteract 5-faces Eighty-four is the sum of the first seven triangular numbers (making it a tetrahedral number), as well as the sum of a twin prime (41 + 43). Being thrice a perfect number, 84 is itself a semiperfect number.

Eighty-four is also the lim sup of the largest finite subgroup of the mapping class group of a genus g surface divided by g.

A hepteract is a seven-dimensional hypercube with 84 penteract 5-faces

In astronomy

• Messier object M84, a magnitude 11.0 lenticular galaxy in the constellation Virgo
• The New General Catalogue object NGC 84, a single star in the constellation Andromeda
• The Saros number of the solar eclipse series which began on -181 April 14 and ended on 1099 May 22. The duration of Saros series 84 was 1280.1 years, and it contained 72 solar eclipses.^[1] Further, the number of the lunar eclipse series which began on -96 September 13 and ended on 1401 February 28. The duration of Saros series 84 was 1496.5 years, and it contained 84 lunar eclipses.^[2]

In sports

Los Angeles Lakers Magic Johnson holds the record for assists in a 6-game NBA Finals Series (1985) with 84

In other fields

dial +84 for Vietnam

Eighty-four is also:

• The year AD 84, 84 BC, or 1984.
• The atomic number of polonium
• The model number of Harpoon missile
• WGS 84 - The latest revision of the World Geodetic System, a fixed global reference frame for the Earth.
• The house number of 84 Avenue Foch
• The number of the French department Vaucluse
• The designation of Interstate 84, two Interstate Highways that run from Oregon to Utah and from Pennsylvania to Massachusetts.
• The code for international direct dial phone calls to Vietnam
• The town of Eighty Four, Pennsylvania
• The company 84 Lumber
• The ISBN Group Identifier for books published in Spain
• A variation of the game 42 played with two sets of dominoes.
• The film "84 Charing Cross Road" (1987) starring Anne Bancroft and Anthony Hopkins
• KKNX Radio 84 in Eugene, Oregon
• The John Larroquette Show ran on NBC from 1993 to 1996 for 84 episodes
• The B-Side to "Up All Night" (Take That song)
• British Army term for the 84mm Carl Gustav recoilless rifle.

References

ab: ar:84 ( ) az:84 ( d d) bo: ( ) ca:Vuitanta-quatre cv:84 ( ) es:Ochenta y cuatro eo:Okdek kvar eu:Laurogeita lau fa: ( ) fr:84 (nombre) gan:84 ko:84 id:84 (angka) ia:84 (numero) it:84 (numero) ht:84 (nonm) lbe: lt:84 (skai ius) hu:84 (sz m) mk:84 ( ) ms:84 (nombor) nl:84 (getal) ja:84 no:84 (tall) pnb:84 pl:84 (liczba) pt:Oitenta e quatro ru:84 ( ) nso:84 (nomoro) sl:84 ( tevilo) srn:Numro 84 sv:84 (tal) th:84 uk:84 ( ) za:Bat cib seiq vi:84 (s ) war:84 (ihap) zh-yue:84 zh:84