39 (number) - Definition and Overview

39 is the natural number following 38 and preceding 40.

In mathematics

Thirty-nine is the sum of five consecutive primes (3 + 5 + 7 + 11 + 13) and the sum of the first three powers of 3 (<math>3^1 + 3^2 + 3^3<math>). Given 39, the Mertens function returns 0.

In science

• The atomic number of yttrium

In astronomy,

Messier object M39, a magnitude 5.5 open cluster in the constellation Cygnus

The New General Catalogue object (http://www.ngcic.org/) NGC 39, a spiral galaxy in the constellation Andromeda

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on -1718 May 26 and ended on -438 July 3. The duration of Saros series 39 was 1280.1 years, and it contained 72 solar eclipses.

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on -1380 March 26 and ended on -82 May 14. The duration of Saros series 39 was 1298.1 years, and it contained 73 lunar eclipses.

In other fields

Thirty-nine is also:

• In the title of the John Buchan novel, The Thirty-Nine Steps.
• The code for international direct-dialed phone calls to Italy.
• I-39 is the designation for a US interstate highway from Normal, Illinois to Wausau, Wisconsin.
• The eternal age of comedian Jack Benny, and many other people as they grow older.
• The traditional number of times citizens of Ancient Rome hit their slaves when beating them, referred to as "Forty save one."
• The year A.D. 39, 39 BC, or 1939.
• Japanese Internet chat slang for "thank you" when written with numbers.