I believe that the raw WD spinup times are in milliseconds.
However, Hitachi's SMART attributes often have several components.
I'm assuming that the spinup time is 12648550, in which case the hexadecimal value is 0x00C10066.http://www.google.com/search?q=12648550+in+hex
Notice that the number consists of two 16-bit parts, namely 0x00C1 (= 193 decimal) and 0x66 (= 102). Therefore the spinup times are a lot less than it would appear.