Fatto matematico: 21347 is an uninteresting number.
Trivia: 21347 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: June 11th is the day in 1963 that Buddhist monk Thich Quang Duc burns himself with gasoline in a busy Saigon intersection to protest the lack of religious freedom in South Vietnam.