Hecho matemático: 21805 is an unremarkable number.
Trivia: 21805 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fecha histórica: September 12th is the day in 1966 that Gemini 11, the penultimate mission of NASA's Gemini program, and the current human altitude record holder (except for the Apollo lunar missions).