here we need to find the wrong number in 12439, 23549, 34659, 45769
as we will add the digits of every number
12439 : 1+2+3+4+9 = 19
23549 : 2+3+5+4+9 = 23
34659 : 3+4+6+5+9 = 27
45769 : 4+5+7+6+9 = 31
As we can see that in very case the sum of digits of number is a prime number except in case of 34659 and hence 34659 is the odd one out
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