Questions One Rarely Thinks To Ask

60 seconds to a minute, 60 minutes to an hour, 24 hours to a day, seven days to a week...

Who came up with these numbers and why? There seems a certain randomness to them. And if they're not random what system is being followed- is it logical, esoteric or attuned to some natural pulse? I note that everything is in sixes until we come to the days the week. So why not 6 days to a week- or 12?

Maths was never my strong point- and it's possible I'm missing something obvious...