Fatto generale: 20191 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20191 is an uninteresting number.
Trivia: 20191 is an unremarkable number.
Data storica: April 12th is the day in 1820 that Alexander Ypsilantis is declared leader of Filiki Eteria, a secret organization to overthrow Ottoman rule over Greece.