UPS tracking number is quite long because it holds a lot of information including UPS Account Number. It usually starts with 1Z and followed by a 6-digit account number and a few more characters to complete the tracking number.
This is an example of a tracking number : 1Z xxx xxx yy zzzz zzz c
xxx xxx = Alphanumeric account number of the shipper
yy = UPS service level
zzzz zzz = Package identifier
c = check digit