divisor

Hello
I need help:

Let
N = (2^(p)1)2^(p-1), where p is prime. Give the elements of the set

S
N
that consists of the divisors of N, others than N :

S
N
= {x1, x2, ..., xn},

with {i = 1, 2...n : xi|N, xi 6= N}. What is the cardinality of SN.

Give
N and SN for p = 2, 5

thank you