Fatto generale: 20459 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20459 is an uninteresting number.
Trivia: 20459 is a boring number.
Data storica: January 5th is the day in 1975 that the Tasman Bridge in Tasmania, Australia, is struck by the bulk ore carrier Lake Illawarra, killing twelve people.