for the particular example given it can be solved in the following way.

let a number .... where 's are primes.

then the number of divisors of n is ...

now here ... =3

so one of is 3. this also means that only one of the is 2 and all others are 0.

so n= for some prime p; 2<n<49.

the only 's which qualify for the above condition are 2,3 and 5.

so the there numbers are 4,9 and 25.