You can't find the precise integer without knowing what the product is - your question is incomplete - but you can find a general solution.
If [tex]x[/tex] is one of the integers, then the next even integer is given by [tex]x+2[/tex]. So if the product is [tex]n[/tex], then you have
[tex]x(x+2)=k\implies x^2+2x=k\implies x^2+2x+1=k+1\implies (x+1)^2=k+1\implies x=-1\pm\sqrt{k+1}[/tex]
Plug in [tex]k[/tex] and select the solution for [tex]x[/tex] that is an even integer.
