784 = 24 × 72 = 282 = 1 3 + 2 3 + 3 3 + 4 3 + 5 3 + 6 3 + 7 3 {\displaystyle 1^{3}+2^{3}+3^{3}+4^{3}+5^{3}+6^{3}+7^{3}}, the sum of the cubes of the first seven positive integers, happy number
