Fatto generale: 68638 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 68638 is a boring number.
Trivia: 68638 is an unremarkable number.
Data storica: December 3rd is the day in 1959 that the current flag of Singapore is adopted, six months after Singapore became self-governing within the British Empire.