Factorization
40 = 2 × 2 × 2 × 5
40 has 8 divisors: 1, 2, 4, 5, 8, 10, 20, 40
Sum of all divisors other than 40:
50
Sums & differences
Sum of 2 squares: 40 = 62 + 22
Difference of 2 squares: 40 = 72 - 32 = 112 - 92
Goldbach conjecture: 40 = 37 + 3 = 29 + 11 = 23 + 17
