TeX source:
73 = 2 ⋅ 36 = 2 ⋅ 2 ⋅ 18 = 2 ⋅ 2 ⋅ 2 ⋅ 9 = 2 ⋅ 2 ⋅ 2 ⋅ 3 ⋅ 3 = 2^3 ⋅ 3^2