Let
N = p1^(a1+1)*p2(a2+1)...pk^ak has 24 positive factors where p1 and p2 are distinct prime numbers.
Given, (a1+1)*(a2+1).....(ak+1) = 24
We are asked to find the minimum pk and maximum pk to get the range
Minimum = p1^(a1+1) => a1+1 = 24 => a1 = 23
=> Minimum PF n can have = 1
To find the maximum distinct PF N can have, we need the largest number of terms in our product.
Prime factorize 24 = 2^3*3
a1 + 1 = 2 => a1 = 1
a2 + 1 = 2 => a2 = 1
a3 + 1 = 2 => a3 = 1
a4 + 1 = 3 => a4 = 2
This means we can have max. 4 distinct PF with powers 1,1,1 and 2
Finally, range = Max - Minimum = 4 - 1 = 3
Option C.
Bunuel
If a positive integer n has 24 positive factors, what is the maximum possible range in the number of distinct prime factors that n can have?
A. 1
B. 2
C. 3
D. 4
E. 5