Fait général: 9723 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 9723 is a value of n for which n and 5n together use each digit 1-9 exactly once.
Culture générale: 9723 is an uninteresting number.
Date historique: August 14th is the day in 1921 that Tannu Tuva, later Tuvinian People's Republic is established as a completely independent country (which is supported by Soviet Russia).