173 (number)

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.
 * a Pythagorean prime
 * a Higgs prime
 * an Isolated Prime
 * a Regular Prime
 * a Sexy Prime
 * a Truncatable 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).
 * the 40th prime number following 167 and preceding 179.

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
 * Kosmos 173 was a soviet union satellite
 * NGC 173 is an unbarred spiral galaxy

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 Oscar-class submarine
 * USNS Provo (T-AG-173) was a U.S. Navy Phoenix-class auxiliary ship following World War II
 * USS Codington (AK-173) was a U.S. Navy Alamosa-class cargo ship during World War II
 * USS Eldridge (DE-173) was a U.S. Navy Cannon-class destroyer escort during World War II
 * USS Etamin (IX-173) was a U.S. Navy Crater-class cargo ship during World War II
 * USS Florence (SP-173) was a U.S. Navy yacht during World War I
 * USS Hyde (APA-173) was a U.S. Navy Haskell-class attack transport ship during World War II
 * USS PC-472 was a 173 ft U.S. Navy submarine chaser during World War II
 * USS Pike (SS-173) was a U.S. Navy Porpoise-class submarine during World War II
 * USS Sproston (DD-173) was a U.S. Navy Wickes-class destroyer 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 173 mi 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