General fact: 173 is the number of players that competed in badminton at the 2008 Summer Olympics in Beijing, China.
Mathematical fact: 173 is a square-free number, divisible by no perfect square.
Trivia: 173 is the Exit status indicated by Mac App Store software when receipt validation fails.
Historical date: June 21st is the day in 1900 that Baron Eduard Toll, leader of the Russian Polar Expedition of 1900, departed Saint Petersburg in Russia on the explorer ship Zarya, never to return.