I was wondering if anyone can help me with the explanation for question 241 in the OG11
If the integer n has exactly three positive divisors, including 1 and n how many positive divisors does n^2 have?
I dont understand the concept that if a no. has 3 positive divisors it is a perfect sq..HOW???WHY??
most nos. have even no. od divisors.
prime nos. have exactly 2 divisors,1 and itself..
Can someone follow the same reasonung and explain the concept to me?