155 (one hundred [and] fifty-five) is the natural number following 154 and preceding 156.
In mathematics
155 is:
- a composite number
- a semiprime.
- a deficient number, since 1+5+31=37<155.
- odious, since its binary expansion has a total of 5 ones in it.
There are 155 primitive permutation groups of degree 81. OEIS: A000019
If one adds up all the primes from the least through the greatest prime factors of 155, that is, 5 and 31, the result is 155. (sequence A055233 in the OEIS) Only three other "small" semiprimes (10, 39, and 371) share this attribute.
In the military
- USS Capable (AM-155) was a United States Navy Admirable-class minesweeper during World War II
- USS Cole (DD-155) was a United States Navy Wickes-class destroyer during World War II
- USS General A. W. Brewster (AP-155) was a United States Navy General G. O. Squier-class transport during World War II
- USS Hopping (DE-155) was a United States Navy Buckley-class destroyer escort during World War II
- USS Lycoming (APA-155) was a United States Navy Haskell-class attack transport during World War II
- USS Mustang (IX-155) was a United States Navy four-master wooden schooner during World War II
- 155mm artillery, a common caliber
In sports
- The maximum possible score in a single break in snooker, with a free ball at the start of the break (147 is the highest possible without a free ball)
In transportation
- Alfa Romeo 155, a compact executive car produced from 1992 to 1998
- Seattle Bus Route 155
- London Bus Route 155
- The British Rail Class 155 is a diesel multiple unit British train
- Blériot 155 was a French airliner of the 1920s
- 155th Street, Manhattan, New York
- 155th Street New York City Subway stations:
In other fields
155 is also:
- The year AD 155 or 155 BC
- 155 is the number for the International Operator in the United Kingdom
- 155 is the number for the emergency medical services in the Czech Republic and Slovakia
- 155 AH is a year in the Islamic calendar that corresponds to 771–772 CE
- 155 Scylla is a main belt asteroid
- Europium-155 is a radioisotope or Europium and fission product with a half-life of 4.76 years
- 155, a 2007 song by the band +44
- The dialing code for Obihiro, Japan
- The atomic number of an element temporarily called unquintquinttium
- 155 North Wacker is a 46-story skyscraper in Chicago
- Wolseley No. 155, Saskatchewan, is a rural municipality in Canada
See also
- List of highways numbered 155
- United Nations Security Council Resolution 155
- United States Supreme Court cases, Volume 155
- Psalms 152–155
- McHenry County, Illinois Community High School District 155