I don't know what that number represents; For a MySQL like database the
tutorial describes the date datatype.
By looking at the number and trying "semirandom" stuff; perhaps to get the year in php
$year = floor(1970 + $stamp/(60*60*365*24))
$day = floor(365.0*(1970 + $stamp/(60*60*365*24) - $year))
$hour = floor( ((365.0*(1970 + $stamp/(60*60*365*24) - $year)) - $day)*24.0)
I guess you can go from there to figure out the minutes & seconds.