52 (number)

52 (fifty-two) is the natural number following 51 and preceding 53.

[edit] In mathematics

Fifty-two is the 5th Bell number and a decagonal number. It is an untouchable number, since it is never the sum of proper divisors of any number, and it is a noncototient since it is never the answer to the equation x - φ(x).

Messier object M52, a magnitude 8.0 open cluster in the constellation Cassiopeia, also known as
The New General Catalogue object NGC 52, a spiral galaxy in the constellation Pegasus
The Saros number of the solar eclipse series which began on -1378 August 14 and ended on 155 February 19. The duration of Saros series 52 was 1532.5 years, and it contained 86 solar eclipses. The Saros number of the lunar eclipse series which began on -1026 May 27 and ended on 204 June 29. The duration of Saros series 52 was 1280.1 years, and it contained 72 lunar eclipses.

The piano has 52 white keys

Fifty-two is:

The approximate number of weeks in a year. 52 weeks equal 364 days, while the tropical year is 365.24 days long. According to ISO 8601, most years have 52 weeks while some have 53.
The number of countries in Africa
The number of sons of Nebo in the Census of men of Israel upon return from exile (Holy Bible, Ezra 2:29)
A significant number in the Maya calendar
On the piano, the number of white keys (notes in the C major scale)
The number of cards in a standard deck of playing cards, not counting Jokers or advertisement cards
The name of a practical joke card game 52 Pick-up
"52-Pickup" is a film starring Roy Scheider
The code for international direct dial phone calls to Mexico
A comic series from DC Comics entitled 52 has 52 issues.
A second comic series from DC Comics entitled Countdown will also have 52 issues, counting down from Issue #51 to #0.
The number of letters in the English alphabet, if majuscules are distinguished from minuscules

Manhattan's 52nd Street between 5th and 7th Aves was known as Swing Street during the 1930s and 1940s
Billy Joel CD "52nd Street"

For over twenty years, 52 was the best-known car number of retired NASCAR driver Jimmy Means
Number worn by Ray Lewis of the Baltimore Ravens in the NFL
Number worn by Frank Gatski of the Cleveland Browns in the NFL
Number worn by Todd Fuller, of the Charlotte Hornets in the NBA
Number worn by Buck Williams of the Nets in the NBA
Number worn by Craig Rivet of the Montreal Canadiens in the NHL