Fatto generale: 726 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 726 is the number of 4-step self-avoiding walks on the cubic lattice.
Trivia: 726 is a boring number.
Data storica: December 26th is the day in 1998 that Iraq announces its intention to fire upon U.S. and British warplanes that patrol the northern and southern no-fly zones.