Hecho matemático: 1665 is the number of triangles of any size contained in the triangle of side 18 on a triangular grid.
Trivia: 1665 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fecha histórica: July 22nd is the day in 1793 that Alexander Mackenzie reaches the Pacific Ocean becoming the first Euro-American to complete a transcontinental crossing of Canada.