Fatto generale: 21386 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21386 is an uninteresting number.
Trivia: 21386 is an uninteresting number.
Data storica: July 20th is the day in 1980 that the United Nations Security Council votes 14-0 that member states should not recognize Jerusalem as the capital of Israel.