Fait mathématique: 21296 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Culture générale: 21296 is an unremarkable number.
Date historique: April 21st is the day in 1863 that Bahá'u'lláh, the founder of the Bahá'í Faith, declares his mission as "He whom God shall make manifest".