big fan
and 21 cause 3x7=21 which is like wow very sexy multiplication going on. 21 is also in the fibonacci sequence and looks like she would be a prime number but her factors are 1,3,7 and 21 which is like oh ok!
its only factors apart from 1 and itself are 3 and 7 which are both prime numbers and pretty cool as well. plus it’s the 8th number in the fibonacci sequence! i also had a twenty one pilots phase when i was 12 and yeah all the other reasons are kinda the intellectualising of this.