5^6 - 1 is divisible by

• Divisibility

5⁶ - 1 is divisible by

1. 5
2. 13
3. 31
4. None of these

Answer

5⁶ - 1 = (5³ - 1)(5³ + 1) = 124*126

124 is divisible by 31.

The correct option is C.