181 (number)

← 180 181 182 →
← 180 181 182 183 184 185 186 187 188 189 → List of numbers — Integers ← 0 100 200 300 400 500 600 700 800 900 →
Cardinal	one hundred eighty-one
Ordinal	181st (one hundred and eighty-first)
Factorization	prime
Prime	42nd
Divisors	1, 181
Roman numeral	CLXXXI
Binary	101101012
Ternary	202013
Quaternary	23114
Quinary	12115
Senary	5016
Octal	2658
Duodecimal	13112
Hexadecimal	B516
Vigesimal	9120
Base 36	5136

181 (one hundred [and] eighty-one) is the natural number following 180 and preceding 182.

In mathematics

• 181 is an odd number
• 181 is a centered number
  • 181 is a centered pentagonal number^[1]
  • 181 is a centered 12-gonal number^[2]
  • 181 is a centered 18-gonal number^[3]
  • 181 is a centered 30-gonal number
  • 181 is a centered square number^[4]
  • 181 is a star number that represents a centered hexagram (as in the game of Chinese checkers)
• 181 is a deficient number, as 1 is less than 181
• 181 is an odious number
• 181 is a prime number
  • 181 is a Chen prime^[5]
  • 181 is a dihedral prime
  • 181 is a full reptend prime^[6]
  • 181 is a palindromic prime
  • 181 is a strobogrammatic prime, the same when viewed upside down
  • 181 is a twin prime with 179
• 181 is a square-free number
• 181 is an undulating number, if written in the ternary, the negaternary, or the nonary numeral systems
• 181 is the difference of 2 square numbers: 91² – 90²
• 181 is the sum of 2 consecutive square numbers: 9² + 10²
• 181 is the sum of 5 consecutive prime numbers: 29 + 31 + 37 + 41 + 43

In geography

• Langenburg No. 181, Saskatchewan rural municipality in Saskatchewan, Canada
• 181 Fremont Street proposed skyscraper in San Francisco, California
• 181 West Madison Street, Chicago

In the military

• 181st (Brandon) Battalion, CEF was a unit in the Canadian Expeditionary Force during World War I
• 181st Airlift Squadron is a unit of the Texas Air National Guard
• 181st Infantry Brigade of the United States Army based at Fort McCoy, Wisconsin
• 181st Intelligence Wing is a unit of the United States Air Force located at Hulman Field, Terre Haute, Indiana
• AN/APQ-181 an all-weather, low probability of intercept (LPI) radar system for the U.S. Air Force B-2A Spirit bomber aircraft
• Bücker Bü 181 Bestmann single-engine trainer aircraft during World War II
• USNS Adelphi (T-AG-181) was a ship scheduled to be acquired by the U.S. Navy, however, the program was cancelled
• USNS Fred C. Ainsworth (T-AP-181) was a United States Navy troop transport during World War II
• USNS Potomac (T-AO-181) was a United States Navy Oiler following the Vietnam War
• USS Accokeek (ATA-181) was a United States Navy ATA-174 class auxiliary ocean tugboat during World War II
• USS Flagler (AK-181) was a United States Navy Alamosa-class cargo ship following World War II
• USS Hopewell (DD-181) was a United States Navy Wickes class destroyer following World War I
• USS Pompano (SS-181) was a United States Navy Porpoise-class submarine during World War II
• USS Straub (DE-181) was a United States Navy Cannon-class destroyer escort during World War II

In movies

• “181: Fragments of a Journey in Palestine-Israel,” winner of the 2005 Yamagata International Documentary Film Festival
• The war film “The Enemy Below” revolves around the fictitious Buckley-class destroyer escort, the USS Hayes (DE-181) and a German U-boat

In sports

• Retired American Thoroughbred horse racing jockey Randy Romero won a track record 181 races at the Fair Grounds Race Course in New Orleans

In transportation

• The Volkswagen 181
• Lufthansa Flight 181, which was hijacked on October 13, 1977
• London Buses route 181
• 181 Union City-New York, a New Jersey Transit bus route from New Jersey to New York
• The Córas Iompair Éireann CIE 181 Class diesel locomotives, and numbered B181 to B192, built by General Motors Electro-Motive Division (EMD) in 1966
• East 181st Avenue, a light rail station on the MAX Blue Line in Gresham, Oregon
• New York City Subway stations in Manhattan:
  • 181st Street (IND Eighth Avenue Line), at Fort Washington Avenue served by the A train
  • 181st Street (IRT Broadway – Seventh Avenue Line), at St. Nicholas Avenue served by the 1 train
• 181st Street (Manhattan)
• Oregon Route 229, also known as the Siletz Highway No. 181

In other fields

181 is also:

• The year AD 181 or 181 BC
• The atomic number of an element temporarily called Unoctunium
• 181 Eucharis is a large K-type Main belt asteroid
• Minuscule 181 (in the Gregory-Aland numbering), α 101 (Soden), is a Greek minuscule manuscript of the New Testament
• Mir-181 microRNA precursor is a small non-coding RNA molecule

See also

• List of highways numbered 181
• United Nations Security Council Resolution 181
• United Nations General Assembly Resolution 181 (II) Future Government of Palestine
• United States Supreme Court cases, Volume 181
• Pennsylvania House of Representatives, District 181
• Criminal Code of Belarus, Article 181
• Constitution of Malaysia, Article 181

References

1. "Sloane's A005891 : Centered pentagonal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-26.
2. "Sloane's A003154 : Centered 12-gonal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-26.
3. "Sloane's A069131 : Centered 18-gonal numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-26.
4. "Sloane's A001844 : Centered square numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-26.
5. "Sloane's A109611 : Chen primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-26.
6. "Sloane's A001913 : Full reptend primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-26.

External links

• Number Facts and Trivia: 181
• The Number 181
• The Positive Integer 181
• Prime curiosities: 181
• VirtueScience: 181
• Number Gossip: 181
• 181 FM Internet radio