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It is 64 which is also a square number
Any number squared except 0 is a perfect square so it follows that prime numbers are less common than perfect squares.
A perfect number is a positive integer that is equal to the sum of its proper divisors (excluding itself). The first four perfect numbers are 6, 28, 496, and 8128. These are the only known perfect numbers less than 50. Perfect numbers are rare and have special properties in number theory.
There are 1,963 such integers. Every factor of a number has a pair. The only time there will be an odd number of factors is if one factor is repeated, ie the number is a perfect square. So the question is really asking: how many positive integers less than 2008 (in the range 1 to 2007) are not perfect squares. √2007 = 44 and a bit (it lies between 44 and 45) So there are 44 integers less than (or equal to) 2007 which are perfect squares → 2007 - 44 = 1963 integers are not perfect squares in the range 1-2007 and have an even number of factors (divisors).
A perfect number equals the sum of its proper divisors. A deficient number is greater than the sum of its proper divisors. An abundant number is less than the sum of its proper divisors. Proper divisors of a number do not include the number itself.