Suppose that the prime factors of an odd number only occur once in its prime factorization, so that n=p1xp2xp3xp4x...

for prime integers p1,p2,p3,...

What must be true about the average of all the positive integer factors of n?

Correct answer is : The average of the positive integer factors of n will be a whole number.

Couldn't understand the explanation provided. Could you explain for explicit?

For example n=5x7x11, the average sum should be (5+7+11)/3 isn't an integer?