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84 (number)

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Title: 84 (number)  
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Subject: 83 (number), 85 (number), 80 (number), 81 (number), 82 (number)
Collection: Integers
Publisher: World Heritage Encyclopedia

84 (number)

83 84 85
Cardinal eighty-four
Ordinal 84th
Factorization 22× 3 × 7
Divisors 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
Roman numeral LXXXIV
Binary 10101002
Ternary 100103
Quaternary 11104
Quinary 3145
Senary 2206
Octal 1248
Duodecimal 7012
Hexadecimal 5416
Vigesimal 4420
Base 36 2C36

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


  • In mathematics 1
  • In astronomy 2
  • In other fields 3
  • See also 4
  • References 5

In mathematics

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

84 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.

84 is 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

In other fields

Eighty-four is also:

See also


  1. ^
  2. ^
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