If this is a 6 sided die then the only possible roll that isnt an odd, a 2, or a 4 is 6.
The probability of something happening is also the probability of something not happening. So in order to not roll an odd, a 2 or a 4 in two rolls, you have to roll a 6 twice.
Since a side is only 6 inches long and the total perimeter is 36; take 36/6 and you get 6. The only figure with six sides is a hexagon, thus your answer is hexagon.