55 (number)

55 is

• the fifteenth discrete semiprime (${\displaystyle 5\times 11}$) and the second with 5 as the lowest non-unitary factor thus of the form (5.q), where q is a higher prime.
• with an aliquot sum of 17; a prime, within an aliquot sequence of one composite number (55, 17, 1,0) to the Prime 17 in the 17-aliquot tree.
• a triangular number (the sum of the consecutive numbers 1 to 10), and a doubly triangular number.[1]
• the 10th Fibonacci number.[2] It is the largest Fibonacci number to also be a triangular number.
• a square pyramidal number (the sum of the squares of the integers 1 to 5)[3] as well as a heptagonal number,[4] and a centered nonagonal number.[5]
• in base 10, a Kaprekar number.[6]
• the product of 5 and 11, 5 being the prime index of 11.
• the first number to be a sum of more than one pair of numbers which mirror each other (23 + 32 and 14 + 41).

• The atomic number of caesium.

• The name of a song by Kasabian. The song was released as a B side to Club Foot and was recorded live when the band performed at London's Brixton Academy.
• "55", a song by Mac Miller
• "I Can't Drive 55", a song by Sammy Hagar
• "Ol' '55", a song by Tom Waits
• Ol' 55 (band), an Australian rock band.
• Primer 55 an American band
• Station 55, an album released in 2005 by Cristian Vogel
• 55 Cadillac, an album by Andrew W.K.

• In the United States, the National Maximum Speed Law prohibited speed limits higher than 55 miles per hour (90 km/h) from 1974 to 1987

• 55 Days at Peking a film starring Charlton Heston and David Niven

• AD 55
• 55 BC
• 1755
• 1855
• 1955

• Gazeta 55, an Albanian newspaper
• Agitation and Propaganda against the State, also known as Constitution law 55, a law during Communist Albania.
• The code for international direct dial phone calls to Brazil
• A 55-gallon drum for containing oil, etc.
• The Élysée, the official residency of the French Republic president, which address is 55 rue du Faubourg-Saint-Honoré in Paris.

• 55th Regiment of Foot (disambiguation)
• Channel 55 (disambiguation)
• Type 55 (disambiguation)
• Class 55 (disambiguation)
• List of highways numbered 55