52 (number) - Definition and Overview

52 is the natural number following 51 and preceding 53.

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).

In science

• The atomic number of tellurium

In astronomy,

Messier object M52, a magnitude 8.0 open cluster in the constellation Cassiopea, also known as

The New General Catalogue object (http://www.ngcic.org/) NGC 52, a spiral galaxy in the constellation Pegasus

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) 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 (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) 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.

In other fields

Fifty-two is also:

• The number of weeks in a year.
• The number of sons of Nebo in the Census of men of Israel upon return from exile (Holy Bible, Ezra 2:29).
• 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.
• The code for international direct dial phone calls to Mexico.

• The year AD 52, 52 BC, and 1952.