Fatto generale: 21818 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21818 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 21818 is a boring number.
Data storica: September 25th is the day in 1959 that Solomon Bandaranaike, Prime Minister of Sri Lanka is mortally wounded by a Buddhist monk, Talduwe Somarama, and dies the next day.