47^43 + 43^43 is divisible by:

Correct answer: 90. For an odd power n, aⁿ + bⁿ is divisible by a + b. Here 47 + 43 = 90, so the sum is divisible by 90.

• 43: 43 divides 43^43 but not 47^43, so it does not divide the sum.
• 47: 47 divides 47^43 but not 43^43, so it does not divide the sum.
• 1013: No rule makes this sum divisible by 1013.