Which number doesn't belong and why? 23, 41, 89, 11, 43, 131

Answer 1

where if you multiply it by 2 and add 1, you still have a prime number.

23*2+1=47
41*2+1=83
89*2+1=179
11*2+1=23
131*2+1=263

but

43*2+1=87