2,004,717,056 seconds is 63.569 years. Stephen Hawking died at 76. 76 minus 63.569 is 12.43.
He was diagnosed when he was 21, so the spell duration should be 1,734,480,000 seconds.
It doesn’t say “paralyze…” it says “chance to…” so maybe it is multiplying that chance to paralyze times the number of seconds to come up with your estimate of how long he was paralyzed. It is the expected number of seconds of paralysis time to compensate for the risk of it not triggering.
Paralyzing is super broken in Skyrim. It doesn’t actually matter how long the target is paralyzed, because paralyzing them at all causes them to fall, starting a lengthy stand-up animation, during which they’re vulnerable. Hit them, they fall. They start to get back up, so you hit them more. Eventually, they stay down.
I guess you can say… they get knocked down and do NOT get up again