Which of the following numbers doesn't have a divisor greater than 1 that is the square of an integer?	Pick one: A) 63 B) 108 C) 25 D) 13 E) 36
Prime Factorization   63=7*3*3= 7*3^2. Includes the perfect square of 9.   108=2*3*2*3*3=6^2*3. Includes the perfect square of 36.   25=5*5=5^2. A perfect square of 25.   13=13*1. There are no perfect squares as factors.   36=2*2*3*3= 2^2*3^2. Includes the perfect squares of 4 and 9.   Only 13 does not have a perfect square as a factor so the correct answer is 13.
<result>D</result>
Which of the following numbers doesn't have a divisor greater than 1 that is the square of an integer?