173 (number)

In mathematics

• an odd number.
• a deficient number.
• an odious number.
• a balanced prime.
• an Eisenstein prime with no imaginary part.
• a Sophie Germain prime.
• an inconsummate number.
• the sum of 2 squares: 2² + 13².
• the sum of three consecutive prime numbers: 53 + 59 + 61.
• palindromic in bases 3, 9 and 172.

  In astronomy

• 173 Ino is a large dark main belt asteroid
• 173P/Mueller is a periodic comet in our solar system
• Arp 173 is a pair of galaxies in the constellation Boötes

  In the military

• 173rd Air Refueling Squadron unit of the Nebraska Air National Guard
• 173rd Airborne Brigade Combat Team of the United States Army based in Vicenza
• 173rd Battalion unit of the Canadian Expeditionary Force during the World War I
• 173rd Surveillance Squadron of the Australian Army at Oakey, Queensland
• K-173 Chelyabinsk Russian
• was a U.S. Navy Phoenix-class auxiliary ship following World War II
• was a U.S. Navy during World War II
• was a U.S. Navy during World War II
• was a U.S. Navy during World War II
• was a U.S. Navy yacht during World War I
• was a U.S. Navy ship during World War II
• was a U.S. Navy submarine chaser during World War II
• was a U.S. Navy Porpoise-class submarine during World War II
• was a U.S. Navy following World War II
• Vought V-173 was a U.S. Navy experimental test aircraft during World War II

  In transportation

• The Georgia Railroad, the world longest railroad in 1845, ran for from Augusta to Marthasville
• United Airlines Flight 173 en route from Denver to Portland crashed on December 28, 1978
• The Velocity 173 was a kit aircraft produced by Velocity Aircraft in the early '90s.

  In Popular Culture

• The book "173 Hours in Captivity"
• SCP-173, a dangerous anomalous statue captured by the fictional SCP Foundation

  In other fields

• The year AD 173 or 173 BC
• 173 AH is a year in the Islamic calendar that corresponds to 789 - 790 CE
• The atomic number of an element temporarily called Unsepttrium
• Topic of discussion during the podcast "Skeptics with a K" episode 180