The date function expects a time value in the form of a Unix timestamp. The number should be the number of seconds between your date and the Unix Epoch (January 1 1970 00:00:00 GMT). So the timestamp 25017 translates to Thursday, January 1st 1970, at 6:56:57 (GMT). You probaly got 1:56:57 cause your on one of the USA times rather than GMT.
Today's date, Saturday, August 6th 2005, 0:43:15 (GMT) translates to 1123288995. Clearly a much bigger number than you have.