...Yeah, or perhaps it's a secret telephone number. Or maybe they just accidentally wrote all these numbers and now they're sitting and laughing at our ideas ;) Seriously, why would they call a song "Silence i" or "Silence 2363841"? :)
If we remove the seemingly out-of-place 7, the sequence becomes eight binary digits (a byte) with a decimal value of 105 (equal to a hexadecimal value of 69). In ASCII, this value is represented by a lowercase 'i'. So perhaps the true title is "Silence i". The presence of the 7 could be an allusion the the seven individuals comprising Unexpect.
On the back of the CD case, you'll see an underscore. When I ripped it from the CD, there was an underscore. Inside the pamphlet, it has it written without an underscore. It seems that either is correct. No need to freak out.