A solution of silver nanoprisms that are approximately 40 nm in length displays a purple color. Calculate the number of silver atoms in a single silver nanoprism with the shape of an equilateral triangle with an edge length of 40 nm and a thickness of 5 nm. The density of silver is 10.5 g/cm^3. and the area of an equilateral triangle is :sqrt((3)/4)a^2 where a = edge length of the triangle