69 (number) - Definition and Overview

69 is the natural number following 68 and preceding 70.

It is the largest number whose factorial is less than 10¹⁰⁰ (69! ≈ 1.71x10⁹⁸). This means it is often the largest factorial that can be calculated by a pocket calculator.

It also has the amusing property of being the only number whose square and cube contain once and only once all numerals from zero to nine when written in decimal notation:

• 69² = 4761
• 69³ = 328509

In science

• The atomic number of thulium, a lanthanide

In astronomy,

Messier object M69, a magnitude 9.0 globular cluster in the constellation Sagittarius

The New General Catalogue object (http://www.ngcic.org/) NGC 69, a 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 -742 November 28 and ended on 665 March 22. The duration of Saros series 69 was 1406.3 years, and it contained 79 solar eclipses.

The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on -548 July 3 and ended on 768 September 1. The duration of Saros series 69 was 1316.2 years, and it contained 74 lunar eclipses.

In other fields

Sixty-nine is:

• A sex position in which the participants stimulate each others' sex organs with their mouths.
• Part of the title of 69 Année érotique by Serge Gainsbourg.
• The designation of US Interstate 69, a freeway that runs from Indiana to Michigan.
• The registry of the U.S. Navy's nuclear aircraft carrier USS Dwight D. Eisenhower (CVN-69), named after U.S. President Dwight D. Eisenhower.
• Part of the name of a brand of whisky, Vat 69.
• The number of the French department Rhône.
• In Bill & Ted's Excellent Adventure, the number past and present Bill and Ted are thinking of when questioned by future Bill and Ted to confirm their identity (presumably because of its meaning as a sex position).
• The album 69 Love Songs by The Magnetic Fields.
• The highest numbered channel on the UHF analog television broadcast spectrum, after the spectrum previously assigned to channels 70-83 was reallocated for use by cellular phone services.
• The year AD 69, 69 BC, or 1969.