A fine number, and I think this kid would agree with you.
[video=youtube;pFlcqWQVVuU]http://www.youtube.com/watch?v=pFlcqWQVVuU[/video]
To keep within the rules I shall now get... back on topic about...my favorite number... well as i grew up I would often had nightmares about the number 1 chasing me but then number 2 killed number 1 ! So 2 became even more respected.
Mine is 1 + sqrt(5)/2, or 1.608339887..., which is the Golden Ratio. It has a number of applications in mathematics and science, and is overall an interesting number, and ratio. Most notably are its relevance to biology and anatomy, as well as a variety of other fields.
7, cause luck.
12, cause my birthday, and was considered the "Perfect Number" in the Old World. (Hence, making the number directly after it, 13, the opposite)
21, cause age.