Fatto matematico: 2221 is a value of n for which s(n) is a repdigit.
Trivia: 2221 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: January 29th is the day in 1943 that the first day of the Battle of Rennell Island, U.S. cruiser Chicago is torpedoed and heavily damaged by Japanese bombers.