81 may refer to: *

81 (number) 81 (eighty-one) is the natural number following 80 (number), 80and preceding 82 (number), 82. In mathematics 81 is: * the square number, square of 9 (number), 9 and the second fourth-power of a prime; 34. * with an aliquot sum of 40 (number), 40; ...

* one of the years

81 BC __NOTOC__ Year 81 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Decula and Dolabella (or, less frequently, year 673 ''Ab urbe condita''). The denomination 81 BC for this year has been u ...

AD 81 A.D. 81 ( LXXXI) was a common year starting on Monday of the Julian calendar. At the time, it was known as the Year of the Consulship of Silva and Pollio (or, less frequently, year 834 ''Ab urbe condita''). The denomination A.D. 81 for this ye ...

1981 Events January * January 1 ** Greece enters the European Economic Community, predecessor of the European Union. ** Palau becomes a self-governing territory. * January 6 – A funeral service is held in West Germany for Nazi Grand Admiral ...

2081 In contemporary history, the third millennium is the current millennium in the ''Anno Domini'' or Common Era, under the Gregorian calendar. It began on 1 January 2001 (Roman numerals, MMI) and will end on 31 December 3000 (Roman numerals, MMM ...

* The international calling code for

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

* Nickname for the

Hells Angels Motorcycle Club The Hells Angels Motorcycle Club (HAMC) is an international outlaw motorcycle club founded in California whose members typically ride Harley-Davidson motorcycles. In the United States and Canada, the Hells Angels are incorporated as the Hells ...

. "H" is the eighth letter of the alphabet, and "A" is the first. *

81 Terpsichore 81 Terpsichore is a large and very dark main-belt asteroid. It has most probably a very primitive carbonaceous composition. It was found by the prolific comet discoverer Ernst Tempel on September 30, 1864. It is named after Terpsichore, the ...

, a main-belt asteroid *

81 mm mortar An 81-mm mortar is a medium-weight mortar. It is a smooth-bore, muzzle-loading, high-angle-of-fire weapon used for long-range indirect fire support of light infantry, air assault, and airborne units across the entire front of a battalion zo ...

, a military indirect fire weapon

See also