173 (one hundred [and] seventy-three) is the natural number following 172 and preceding 174.
In mathematics
173 is: 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 number in bases 3 (201023) and 9 (2129).
In astronomy
173 Ino is a large dark main belt asteroid
173P/Mueller is a periodic comet in the Solar System
Arp 173 (VV 296, KPG 439) 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 Special Operations Aviation Squadron of the Australian Army
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 (Flying Pancake) 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 (Atlanta, Georgia) 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 1990s.
In popular culture
The book 173 Hours in Captivity (2000) SCP-173, a fictional statue
In other fields
173 is also: 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