599

599 is a prime number.

599 and 601 form a twin prime pair.

599 is a number that cannot be written as a sum of three squares.

599 is a divisor of 19¹³ - 1.

599 is the smallest number whose digits add to 23.

The Administrative building in the town of Saint-Prime, Quebec, is at the street address 599, rue Principale.

Source: Prime Curios!