27 (twenty-seven; Roman numeral XXVII) is the natural number following 26 and preceding 28.

In mathematics[edit]

• Twenty-seven is a cube of 3: . 27 is also ²3 (see tetration). There are exactly 27 straight lines on a smooth cubic surface, which give a basis of the fundamental representation of the E₆ Lie algebra. 27 is also a decagonal number.^[1]
• In decimal, it is the first composite number not divisible by any of its digits.
• It is the radix (base) of the septemvigesimal positional numeral system.
• 27 is the only positive integer that is 3 times the sum of its digits.
• In a prime reciprocal magic square of the multiples of 1/7, the magic constant is 27.
• In the Collatz conjecture (aka the " conjecture"), a starting value of 27 requires 111 steps to reach 1, more than any number smaller than it.
• The unique simple formally real Jordan algebra, the exceptional Jordan algebra of self-adjoint 3 by 3 matrices of quaternions, is 27-dimensional.^[2]
• In decimal, it is a Smith number^[3] and a Harshad number.^[4]
• It is located at the twenty-eighth (and twenty-ninth) digit after the decimal point in π. (3.141592653589793238462643383279...). If you start counting with 0, it is one of few known self-locating strings in pi.
• 27 contains the decimal digits 2 and 7, and is the result of adding together the integers from 2 to 7. ()
• There are 27 sporadic groups, if the Tits group is included.
• For a three-digit number, one rule of divisibility by 27 is if another divisible by 27 can be generated by transferring the first digit onto the end of a number. For example: 27|378 ➜ 27|783 ➜ 27|837^{[clarification needed]}
• Within senary, one can readily test for divisibility by 43 (decimal 27) by seeing if the last three digits of the number match 000, 043, 130, 213, 300, 343, 430, or 513.
• 27 is divisible by the number of prime numbers below it.

In science[edit]

• The atomic number of cobalt.
• The atomic weight of the only stable isotope of aluminum.
• Dark matter is thought to make up 27% of the universe.^[5]

Astronomy[edit]

• The Messier object M27, a magnitude 7.5 planetary nebula in the constellation Vulpecula, also known as the Dumbbell Nebula.
• The New General Catalogue object NGC 27, a spiral galaxy in the Andromeda constellation.
• The Saros number of the solar eclipse series, which began on 1993 March and ended on 713 April^{[clarification needed]}. The duration of Saros series 27 was 1,280.1 years, and it contained 72 solar eclipses. Further, the Saros number of the lunar eclipse series, which began on 1944 July and ended on 411 January.^{[clarification needed]} The duration of Saros series 27 was 1532.5 years, and it contained 86 lunar eclipses.

Electronics[edit]

• The type 27 vacuum tube (valve), a triode introduced in 1927, was the first tube mass-produced for commercial use to incorporate an indirectly heated cathode. This made it the first vacuum tube that could function as a detector in AC-powered radios. Prior to the introduction of the 27, home radios were powered by a set of three or more storage batteries with voltages of 3 volts to 135 volts.

In language and literature[edit]

• The number of letters in the Spanish alphabet.^[6]
• The number of books in the New Testament.

In astrology[edit]

• 27 Nakṣatra or lunar mansions in Hindu astrology.

In art[edit]

Movies[edit]

• Summer, or 27 Missing Kisses
• Chapter 27-I
• 27 Dresses
• Number 27 (written by Michael Palin)

Music[edit]

• "27", a song by Fall Out Boy on the album Folie à Deux
• "27", a song by Passenger on the album Whispers
• "27", a song by Title Fight on the album Shed.^[7]
• "27", a song by Biffy Clyro on the album Blackened Sky
• "27", a song on Machine Gun Kelly's album Bloom
• "27 Jennifers", a song by Mike Doughty on the album Rockity Roll
• 27, an album by South Korean singer Kim Sung-kyu
• 27, an album by Argentine rock band Ciro y los Persas
• Twenty-Seven, an album by The Adicts.
• French rapper Kaaris' signature number is 27, from his zipcode 93270.
• "Twenty Seven Strangers" by Villagers.
• 27, a Boston-based band
• 27, an opera by composer Ricky Ian Gordon and librettist Royce Vavrek
• 27 Club, a list of popular musicians, artists, or actors who died at age 27

Other[edit]

• The Minneapolis-based artist Deuce 7 (a.k.a. Deuce Seven, Twenty Seven, 27).

In sports[edit]

• The value of all the colors in snooker add up to 27.
• The number of outs in a regulation baseball game for each team at all adult levels, including professional play, is 27.
• The New York Yankees have won 27 World Series championships, the most of any team in the MLB.

In other fields[edit]

Twenty-seven is also:

• The 27 Club is a term used to refer to popular musicians who have died at the age of 27.
• A-27, American attack aircraft.
• The total number of letters in the Hebrew alphabet (22 regular letters and 5 final consonants).
• The code for international direct-dial phone calls to South Africa.
• The name of a cigarette, Marlboro Blend No. 27.
• Alternate name for The Hunt, a book by William Diehl.
• The number of the French department Eure.
• Abbé Faria's prisoner number in the book The Count of Monte Cristo.
• One of the anthropomorphic math symbols Lisa Simpson imagines talking to her in The Simpsons episode "Girls Just Want to Have Sums", which, instead of offering the expected pun-based aphorism, rather unhelpfully only says "twenty seven".
• In Stephen King's novel It, It returns every 27 years to Derry.
• 27 is the number of bones in the human hand.^[8]
• Number of planets needed to fuel the Reality Bomb in the episodes The Stolen Earth and Journey's End of Doctor Who (series 4).
• In Muslim beliefs, the rewards for congregational prayer (Salah al jama'ah) is at least 27 times greater than offering the prayer alone at home.^[9]

See also[edit]

• List of highways numbered 27
• List of highways numbered 27A

References[edit]

• Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987), p. 106.
• Mystery of the number 27 - Large collection of 27 related trivia and facts.
• Prime Curios! 27 from the Prime Pages
• The 27 Project - collection of 27 sightings in movies, TV, culture and art