The number $100$ has four perfect square divisors, namely $1,$ $4,$ $25,$ and $100.$ What is the smallest positive integer that has exactly $2$ perfect square divisors?
The smallest number that works is 16.
In the example, the divisors of 100 include 1 and 100.
Using that standard, the smallest integer would be 4
because its perfect square divisors are 1 and 4.
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