Fatto generale: 20490 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20490 is a boring number.
Trivia: 20490 is a boring number.
Data storica: February 5th is the day in 1597 that a group of early Japanese Christians are killed by the new government of Japan for being seen as a threat to Japanese society.