Let the numbers be 2n+1 and 2n-1, an even number -1 and the same even number+1. Two successive odd numbers.
Their product is (2n+1)(2n-1)=4n2-1=323
4n2=324, n2=81, n=9 gives 2n-1=17, 2n+1=19
n=-9 gives 2n-1=-19, 2n+1=-17
The problem says nothing about the restriction to positive integers.