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{{Infobox number
| number = 87
| divisor = 1, 3, 29, 87
}}
'''87''' ('''eighty-seven''') is the [[Natural number|natural number]] following [[86 (number)|86]] and preceding [[88 (number)|88]].

==In mathematics==
'''87''' is:

* the sum of the squares of the first four primes (87 = 2<sup>2</sup> + 3<sup>2</sup> + 5<sup>2</sup> + 7<sup>2</sup>).
* the sum of the sums of the divisors of the first 10 positive integers.<ref>{{Cite OEIS|1=A024916|2=sum_{k=1..n} sigma(k) where sigma(n) = sum of divisors of n}}</ref>
* the thirtieth [[Semiprime|semiprime]],<ref>{{Cite web|title=A001358 - OEIS|url=https://oeis.org/A001358|access-date=2020-08-10|website=oeis.org}}</ref> and the twenty-sixth distinct semiprime<ref>{{Cite web|title=A006881 - OEIS|url=https://oeis.org/A006881|access-date=2020-08-10|website=oeis.org}}</ref> and the eighth of the form (3.q).
* together with [[85 (number)|85]] and [[86 (number)|86]],<ref>{{Cite OEIS|sequencenumber=A056809}}</ref> forms the last semiprime in the 2nd cluster of three consecutive semiprimes; the first comprising [[33 (number)|33]], [[34 (number)|34]], [[35 (number)|35]].
* with an [[Aliquot sum|aliquot sum]] of [[33 (number)|33]]; itself a [[Semiprime|semiprime]], within an [[Aliquot sequence|aliquot sequence]] of five composite numbers (87,[[33 (number)|33]],[[15 (number)|15]],9,4,3,1,0) to the Prime in the 3-aliquot tree.
* 5! - 4! - 3! - 2! - 1! = 87
* the last two decimal digits of [[Graham's number]].

==In sports==
* Cricket in Australia holds 87 as a superstitiously unlucky score and is referred to as "the devil's number". This originates from the fact that 87 is [[13 (number)|13]] runs short of a century. 187, 287, and so on are also considered unlucky but are not as common as 87 on its own.<ref>{{Cite web|first=Sam|last=Ferris|date=2014-11-02|title=The real story behind Australia's unlucky number 87|url=https://www.cricket.com.au/news/the-story-behind-unlucky-number-87/2014-11-02|access-date=2022-01-27|website=cricket.com.au|language=en}}</ref>
* In the National Hockey League, Wayne Gretzky scored a league-high 87 goals with the Edmonton Oilers in the 1983–84 NHL season.

==In other fields==
'''Eighty-seven''' is also:

*The [[Physics:Atomic number|atomic number]] of [[Chemistry:Francium|francium]].
*An answer to a popular puzzle question states 16, 06, 68, 88, xx, 98. The answer is 87 when looked upside down.
*The number of years between the signing of the U.S. Declaration of Independence and the Battle of Gettysburg, immortalized in Abraham Lincoln's Gettysburg Address with the phrase "''Four Score'' and Seven Years ago..."
*The model number of [[Engineering:Junkers Ju 87|Junkers Ju 87]].
*The number of the French department Haute-Vienne.
*The code for international direct dial phone calls to [[Company:Inmarsat|Inmarsat]] and other services.
*The 87 photographic filter blocks visible light, allowing only infrared light to pass.
*The [[ISBN]] Group Identifier for books published in Denmark.
*The opus number of the 24 Preludes and Fugues of Dmitri Shostakovich.
*In model railroading, the ratio of the popular H0 scale is 1:87.<ref>{{cite web |url=http://mrr.trains.com/how-to/get-started/2011/11/your-guide-to-scales-and-gauges |title=Guide to model railroading scales and gauges |work=Model Railroader |date=2 November 2011 |access-date=2 October 2016 |archive-date=22 June 2015 |archive-url=https://web.archive.org/web/20150622045933/http://mrr.trains.com/how-to/get-started/2011/11/your-guide-to-scales-and-gauges |url-status=dead }}</ref> Proto:87 scale claims to offer precise proportions of wheels and tracks of real railroads.
*David Bowie CD (1987) ''Never Let Me Down'' includes the song, "'87 and Cry".
*The 87th United States Congress met from January 3, 1961, to January 3, 1963, during [[Biography:John F. Kennedy|John F. Kennedy]]'s time in office.
*Ed McBain's ''87th Precinct: Lightning'' film starred Randy Quaid (1995).
*87 punch includes one bottle of Bacardi rum (eight years aged) and 7-up (two-liter bottle).
*[[Company:Wenger|Wenger]] Swiss Army Knife version XXL, listed in the ''Guinness Book of World Records'' as the world's most multi-functional [[Engineering:Penknife|penknife]] with 87 tools.
*''Sonnet 87'' by William Shakespeare.
*Vault 87 is a main location in the game ''[[Software:Fallout 3|Fallout 3]]''.
*M87* is the first black hole ever photographed.
*Aragorn's age in ''The Lord of the Rings''.
*"The Bite of '87" in the ''[[Software:Five Nights at Freddy's|Five Nights at Freddy's]]'' series.

== See also ==
* List of highways numbered 87

==References==
{{Reflist}}

{{DEFAULTSORT:87 (Number)}}
[[Category:Integers]]

{{Sourceattribution|87 (number)}}