General fact: 20976 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 20976 is an uninteresting number.
Trivia: 20976 is an unremarkable number.
Historical date: June 5th is the day in 1984 that Prime Minister of India Indira Gandhi orders an attack on the Golden Temple, the holiest site of the Sikh religion.