21? Mine is 6, and that's because my birthday's on the 6th.
I just love the number 6! XD
Mine's 21 because you can divide it by 7 and 3 :) Which is weird because I hate the numbers 7 and 3... But yes, 21 is a good number :D
P.S. Oh yeah, 6th December, I'm nearly done with your birthday one-shot ;D