Fatto generale: 7039 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 7039 is 28156 / 4, and each digit is contained in the equation exactly once.
Trivia: 7039 is a boring number.
Data storica: April 9th is the day in 1937 that the Kamikaze arrives at Croydon Airport in London – it is the first Japanese-built aircraft to fly to Europe.