181 (number)

From Wikipedia, the free encyclopedia
← 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 →
Cardinalone hundred eighty-one
Ordinal181st
(one hundred eighty-first)
Factorizationprime
Prime42nd
Divisors1, 181
Greek numeralΡΠΑ´
Roman numeralCLXXXI
Binary101101012
Ternary202013
Octal2658
Duodecimal13112
HexadecimalB516

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 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 United States 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[permanent dead link],” winner of the 2005 Yamagata International Documentary Film Festival
  • The war film “The Enemy Below” revolves around the fictitious Buckley-class destroyer escort, USS Hayes (DE-181) and a German U-boat

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 (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
  • The number of channels on an older[clarification needed] American television set, with 68 over-the-air television channels (12 VHF channels [2 through 13] and 56 UHF channels [14 through 69]) and 113 cable television channels (channel 1 and channels 14 through 125, excluding VHF channels 2 through 13)[citation needed]

See also[]

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[]

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