86 (number)

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85 86 87
Cardinal eighty-six
Ordinal 86th
Factorization 2 × 43
Divisors 1, 2, 43, 86
Roman numeral LXXXVI
Binary 10101102
Ternary 100123
Quaternary 11124
Quinary 3215
Senary 2226
Octal 1268
Duodecimal 7212
Hexadecimal 5616
Vigesimal 4620
Base 36 2E36

86 (eighty-six) is the natural number following 85 and preceding 87.

In mathematics[edit]

86 is the 25th distinct semiprime and the 13th of the form (2.q). The aliquot sum of 86 is 46 within the aliquot sequence (86,46,26,16,15,9,4,3,1,0) 86 being the 17th composite number in the 3-aliquot tree.

86 is the middle number in the second cluster of three discrete semiprimes between 85 and 87 being themselves discrete semiprimes.

86 is a semiprime, nontotient and a noncototient. It appears in the Padovan sequence, preceded by the terms 37, 49, 65 (it is the sum of the first two of these).

Since it is possible to find sequences of 86 consecutive integers such that each inner member shares a factor with either the first or the last member, 86 is an Erdős–Woods number.

In base 10, it is a happy number and a self number.

86 is a repdigit in base 6 (222).

86 = (8 x 6 = 48) + (4 x 8 = 32) + (3 x 2 = 6). That is, 86 is equal to the sum of the numbers formed in calculating its multiplicative persistence

In science[edit]

86 is the atomic number of radon. There are 86 metals on the modern periodic table.

In slang[edit]

Main article: 86 (term)

To 86 something means "be out of" an item (e.g., restaurants)[1] or banned from an establishment (e.g., casino.) The origin of the phrase is unclear, although the first known recorded instance of the phrase is from a 1944 book.[2]

The term 86 comes form the movie business in Hollywood. When shooting on colour film, a camera needs an 85 filter (amber in colour) to balance the daylight. When moving indoors under tungsten light the filter is removed or replaced with a clear filter and this was referred to as the 86 filter. Therefore 86 came to mean "nothing" or to "get rid of".

In other fields[edit]

Eighty-six can also refer to:

Cultural references[edit]


  1. ^ "eighty-six: verb [86] - WordReference Forums". Forum.wordreference.com. Retrieved 2012-12-04. 
  2. ^ "Etymology of 86". snopes.com. Retrieved 2012-12-04.