Fatto generale: 21212 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21212 is a boring number.
Trivia: 21212 is a boring number.
Data storica: January 27th is the day in 2010 that the 2009 Honduran constitutional crisis ends when Porfirio Lobo Sosa becomes the new President of Honduras.