Fatto generale: 21192 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21192 is an unremarkable number.
Trivia: 21192 is an uninteresting number.
Data storica: January 7th is the day in 1919 that Montenegrin guerrilla fighters rebel against the planned annexation of Montenegro by Serbia, but fail.