89 (number) - Definition and Overview

89 is the natural number following 88 and preceding 90.

In mathematics

Eighty-nine is the 24th prime number, following 83 and preceding 97, a Sophie Germain prime. It is the smallest Sophie Germain prime to start a Cunningham chain of the first kind of six terms, {89, 179, 359, 719, 1439, 2879}.

89 is a Fibonacci number. Its reciprocal has a curious relationship to the Fibonacci sequence F(n):

<math>\frac{1}{89}=\sum_{n=1}^\infty{F(n)\times 10^{-(n+1)}}=0.011235955...<math>

89 is a highly cototient number.

In science

• The atomic number of actinium

In astronomy,

Messier object M89, a magnitude 11.5 elliptical galaxy in the constellation Virgo

The New General Catalogue object (http://www.ngcic.com/) NGC 89, a magnitude 13.5 peculiar spiral galaxy in the constellation Phoenix and a member of Robert's Quartet

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on 18 February 4 and ended on 1316 [[March 24]. The duration of Saros series 89 was 1298.1 years, and it contained 73 solar eclipses.

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on 67 June 15 and ended on 1347 July 23. The duration of Saros series 89 was 1280.1 years, and it contained 72 lunar eclipses.

In other fields

Eighty-nine is also:

• the model number of CBU-89 Gator, TI-89
• part of the name of the baseball team Oklahoma City 89ers (1962-1997)
• the number of the French department Yonne
• the designation of Interstate 89, a freeway that runs from New Hampshire to Vermont
• The ISBN Group Identifier for books published in Korea
• The year AD 89, 89 BC, or 1989.