Which number does not belong

whim (I do not know)

Well, in that case 911

hmm...I had some ideas, but all seems to be wrong
let's start with simple ones: 35, because there is no month with 35 days...

more difficult ones...

if we look every third number it should go...2, 9, 16, 23 (and not 25), BUT, other numbers in that case would go 5,7,12,14,20,22,29...so far so good (+2 +5 +2 +6 +2 +7...) but next number in that option should be 31, and not 35...so if only one number is wrong then this scenario does not work

35... it's the only number that doesn't have another number after it.

Hypothesis 1 (disproved): the digits of the numbers must add up to a prime number. 9, 22 and 35 all fail this test.

Hypothesis 2 (disproved): the digits of the numbers must add up to an odd number. 2, 20, 22, 35 all fail this test.

Hypothesis 3 (unproven): There are two number sequences intermixed:

2, 7, 12, 16, 22, 29 doesnotequal
2+5=7+5=12+5=17+5=22+5=27

5, 9, 14, 20, 25, 35 doesnotequal
5+4=9+5=14+6=20+7=27+8=35

other patterns I'm not seeing?

Hypothesis 4 (not proven): There are three sequences mixed.

2, 9 , 16, 25 (not squares, not adding 7, not adding 7 then 8 then 9)
5, 12, 20, 29 (add 7, then 8, then 9)
7, 14, 22, 35 (not multiples of 7, not adding 7 then 8 then 9)

other patterns I'm not seeing?

Immaculate logic merlin, or could it be 2 the only number that doesn't have a number before it.

i would say 40
if it belonged, whimsical would have typed it.

heheh, good one Pondering