Fatto matematico: 19937 is the largest known Mersenne prime exponent whose digits are all odd (also a circular prime).
Trivia: 19937 is an unremarkable number.
Data storica: August 1st is the day in 1203 that Isaac II Angelus, restored Eastern Roman Emperor, declares his son Alexius IV Angelus co-emperor after pressure from the forces of the Fourth Crusade.