x^2-9=(x-3)(x+3). So for x-3>1, x>4, this cannot be a prime number. When x-3=1, x=4 and the other factor is 7, a prime number. When x-3=-1, x=2 and the expression is |-5|=5, another prime number. When x+3=1, x=-2 and when x+3=-1, x=-4. The expression becomes |-5|=5 and 7. So the product of these is 4*2*-2*-4=64.