Fatto matematico: 1229 is the number of primes less than 10000.
Trivia: 1229 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: May 13th is the day in 2011 that the 2011 Charsadda bombing in the Charsadda District of Pakistan two bombs exploded killing 98 and wounding 140.