Fatto matematico: 21376 is an unremarkable number.
Trivia: 21376 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: July 10th is the day in 138 that Emperor Hadrian dies after a heart failure at Baiae, he is buried at Rome in the Tomb of Hadrian beside his late wife, Vibia Sabina.