MS Excel save the Date values as a days passed from 01/01/1900 (dd/mm/yyyy) i.e.
if you have a value 1 from cell formated as Date in Excel you the real date is 01/01/1900 (dd/mm/yyyy), If You have 38193 in that cell the real date is 25/07/2004 (dd/mm/yyyy). In your case if you receive a value 6541 the real date is 27/11/1917 (dd/mm/yyyy) so if You want to get the real date you must use the following formula:

FUNCTION RealExcelDate(nExcelValue)
RETURN DATE(1900,1,1)+nExcelValue-2