Hecho general: 51039 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 51039 is an uninteresting number.
Trivia: 51039 is an uninteresting number.
Fecha histórica: September 27th is the day in 1949 that the first Plenary Session of the National People's Congress approves the design of the Flag of the People's Republic of China.