Odd man out of the series - 15, 19, 27, 38, 55, 75?

The given series is 15, 19, 27, 38, 55, 75

15

15 + 4 = 19

19 + 8 = 27

27 + 12 = 39

39 + 16 = 55

55 + 20 = 75

Hence, the odd number in the given series is 38.