Fatto generale: 689 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 689 is the smallest number that can be written as the sum of 3 distinct squares in 9 ways.
Trivia: 689 is an unremarkable number.
Data storica: November 19th is the day in 1095 that the Council of Clermont, called by Pope Urban II to discuss sending the First Crusade to the Holy Land, begins.