Fatto generale: 7123 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 7123 is the number of 2-connected graphs with 8 vertices.
Trivia: 7123 is an uninteresting number.
Data storica: July 2nd is the day in 963 that the imperial army proclaims Nicephorus Phocas Emperor of the Romans on the plains outside Cappadocian Caesarea.