The Unix time number is zero at the Unix epoch, and increases by exactly 86400 per day since the epoch. Thus 2004-09-16T00:00:00Z, 12677 days after the epoch, is represented by the Unix time number 12677 * 86400 = 1095292800. This can be extended backwards from the epoch too, using negative numbers; thus 1957-10-04T00:00:00Z, 4472 days before the epoch, is represented by the Unix time number -4472 * 86400 = -386380800.
http://en.wikipedia.org/wiki/Unix_timestamp
i really dont wanna write code that figures out how many days since the unix epoch (Jan 1st, 1970)
so i guess to answer your question...its a big integer