Hecho general: 21835 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 21835 is a boring number.
Trivia: 21835 is an unremarkable number.
Fecha histórica: October 12th is the day in 1979 that the lowest recorded non-tornadic atmospheric pressure, 87.0 kPa (870 mbar or 25.69 inHg), occurred in the Western Pacific during Typhoon Tip.