Fatto matematico: 20513 is an unremarkable number.
Trivia: 20513 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: February 28th is the day in 1998 that First flight of RQ-4 Global Hawk, the first unmanned aerial vehicle certified to file its own flight plans and fly regularly in U.S. civilian airspace.