156 (one hundred [and] fifty-six) is the natural number, following 155 and preceding 157.

In mathematics

156 is an abundant number, a pronic number, a dodecagonal number,^[1] and a refactorable number.

156 is the number of graphs on 6 unlabeled nodes.^[2]

156 is a repdigit in base 5 (1111), and also in bases 25, 38, 51, 77, and 155.

156 degrees is the internal angle of a pentadecagon.

In the military

• Convoy HX-156 was the 156th of the numbered series of World War II HX convoys of merchant ships from Halifax, Nova Scotia to Liverpool during World War II
• The Fieseler Fi 156 Storch was a small German liaison aircraft during World War II
• The German submarine U-156
• USNS Bull Run (T-AO-156) was a United States Navy T2 tanker during World War II
• USS Alamosa (AK-156) was a United States Navy cargo ship during World War II
• USS Captivate (AM-156) was a United States Navy Admirable-class minesweeper during World War II
• USS City of Dalhart (IX-156) was a United States Navy ship during World War II
• USS General D. E. Aultman (AP-156) was a United States Navy General G. O. Squier-class transport during World War II
• USS J. Fred Talbott (DD-156) was a United States Navy Wickes-class destroyer during World War II
• USS Luiseno (ATF-156) was a United States Navy Abnaki-class tug during World War II
• USS Mellette (APA-156) was a United States Navy Haskell-class attack transport during World War II
• USS Reeves (DE-156) was a United States Navy Buckley-class destroyer escort during World War II
• USS Winchester (SP-156) was a United States Navy fast civilian yacht during World War I

In music

• 156, a song by the Danish rock band Mew appearing in both their 2000 album Half the World Is Watching Me and their 2003 album Frengers.
• NM 156, a 1984 song by the heavy metal band Queensrÿche from the album The Warning
• 156, a song by the Polish Black Metal band Blaze of Perdition from the 2010 album Towards the Blaze of Perdition

In transportation

• The Alfa Romeo 156 car produced from 1997 to 2006.
• The Ferrari 156 was a racecar made by Ferrari from 1961 to 1963.
• The Ferrari 156/85 was a Formula One car in the 1985 Formula One season.
• The Class 156 "Super Sprinter" DMU train.
• The Midland Railway 156 Class, a 2-4-0 tender engine built in the United Kingdom between 1866 and 1874.
• London Buses route 156.
• Martin 156, known as the Russian clipper, was a large flying boat aircraft intended for transoceanic service.

In other fields

156 is also:

• The year AD 156 or 156 BC
• 156 AH is a year in the Islamic calendar that corresponds to 772 – 773 CE
• 156 Xanthippe is a main belt asteroid with a dark surface
• The number of hourly gongs a clock strikes in one day (78 AM gongs and 78 PM gongs)
• The number of sons of Magbish in the Census of the men of Israel upon return from exile (Bible, Ezra 2:30)
• United States DS-156 visa issued for U.S. Department of State Nonimmigrant Visa Application
• The atomic number of an element temporarily called Unpenthexium.^[3]
• The Indian Head No. 156, Saskatchewan rural municipality in the Canadian province of Saskatchewan