Fatto matematico: 9726 is the smallest number in base 5 whose square contains the same digits in the same proportion.
Trivia: 9726 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: August 17th is the day in 986 that a Byzantine army is destroyed in the pass of Trajan's Gate by the Bulgarians under the Comitopuli Samuel and Aron.