General fact: 220 is the SMTP code meaning "service ready".
Mathematical fact: 220 is a composite number, with its divisors being 1, 2, 4, 5, 10, 11, 20, 22, 44, 55 and 110, making it an amicable number with 284.
Trivia: 220 is the common voltage in many countries.
Historical date: August 7th is the day in 626 that the Avar and Slav armies leave the siege of Constantinople.