The answer you are looking for is 36.
If you line up the numbers numerically (4, 8, 16, 32, 36, 64), you'll see that there's a pattern. Each number, multiplied by 2, gets the next number in the sequence. 4 * 2 = 8, 8 * 2 = 16, 16 * 2 = 32, and 32 * 2 = 64.
Thus meaning 36 is the odd number out. I hope this helps!