Why is my solution to this problem wrong?

Question

Algorithms

Problem
My solution
For example, with d = 3, the author's solution gives 55 and I have 28. It seems to me that I did not quite understand the problem. Help me please.

Answer 1

28 is not suitable here, because the number must have at least 4 divisors and all divisors differ by at least d.
28 has six factors (1, 2, 4, 7, 14, 28). Among them there are divisors 1 and 2, which differ by less than d=3.