Fatto matematico: 6663 is a value of n for which s(n) is a repdigit.
Trivia: 6663 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: March 29th is the day in 1867 that Queen Victoria gives Royal Assent to the British North America Act which establishes the Dominion of Canada on July 1.