Fait général: 21300 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 21300 is a boring number.
Culture générale: 21300 is an uninteresting number.
Date historique: April 25th is the day in 1644 that the Chongzhen Emperor, the last Emperor of Ming Dynasty China, commits suicide during a peasant rebellion led by Li Zicheng.