Fatto generale: 20109 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20109 is an uninteresting number.
Trivia: 20109 is a boring number.
Data storica: January 20th is the day in 1972 that Pakistan launched its Nuclear detterent program few weeks after its defeat in Bangladesh Liberation War and Indo-Pakistani War of 1971.