Fatto generale: 21206 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21206 is an uninteresting number.
Trivia: 21206 is an unremarkable number.
Data storica: January 21st is the day in 2003 that a 7.6 magnitude earthquake strikes the Mexican state of Colima, killing 29 and leaving approximately 10,000 people homeless.