Fait général: 21597 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 21597 is an unremarkable number.
Culture générale: 21597 is a boring number.
Date historique: February 16th is the day in 1987 that the trial of John Demjanjuk, accused of being a Nazi guard dubbed "Ivan the Terrible" in Treblinka extermination camp, starts in Jerusalem.