php reader read date from excel

$excel_date = 43010; //here is that value 41621 or 41631
$unix_date = ($excel_date - 25569) * 86400;
$excel_date = 25569 + ($unix_date / 86400);
$unix_date = ($excel_date - 25569) * 86400;
echo gmdate("Y-m-d", $unix_date);

//result is 2017-10-02