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

In mathematics[edit]

Fifty-two is the 6th 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).

In science[edit]

• The atomic number of tellurium

Astronomy[edit]

• 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. 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. The duration of Saros series 52 was 1280.1 years, and it contained 72 lunar eclipses.

In other fields[edit]

• U.S. Route 52 that runs from South Carolina to North Dakota

The piano has 52 white keys

Fifty-two is:

• The approximate number of weeks in a year. 52 weeks is 364 days, while the tropical year is 365.24 days long. According to ISO 8601, most years have 52 weeks while some have 53.
• 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 Pickup
• "52 Pick-Up" is a film starring Roy Scheider and Ann Margaret
• The code for international direct dial phone calls to Mexico
• A weekly comic series from DC Comics entitled 52 has 52 issues, with a plot spanning one full year.
• The number of letters in the English alphabet, if majuscules are distinguished from minuscules
• The number of the French department Haute-Marne
• 52nd Street (disambiguation)

Sports[edit]

• 52 Hand Blocks, a variant of the martial art jailhouse rock.
• For over twenty years, 52 was the best-known car number of retired NASCAR driver Jimmy Means
• 52 American hostages were held in the Iranian Hostage Crisis

Historical years[edit]

52 B.C., 52 A.D., 1952, 2052, etc.

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