General fact: 6791 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 6791 is a value of n for which n and 8n together use each digit 1-9 exactly once.
Trivia: 6791 is a boring number.
Historical date: August 4th is the day in 1863 that Matica slovenská, Slovakia's public-law cultural and scientific institution focusing on topics around the Slovak nation, is established in Martin.