PHP convert milliseconds to mins and seconds

Question

i want to convert millisecond to Hour:Min:Second, for that i'm using this function but that return 387:24:54.834 for 1394694855.

i'm testing and running on localhost

REQUEST_TIME    1394694855

static function formatMilliseconds($milliseconds) 
{
    $seconds = floor($milliseconds / 1000);
    $minutes = floor($seconds / 60);
    $hours = floor($minutes / 60);
    $milliseconds = $milliseconds % 1000;
    $seconds = $seconds % 60;
    $minutes = $minutes % 60;

    $format = '%u:%02u:%02u.%03u';
    $time = sprintf($format, $hours, $minutes, $seconds, $milliseconds);
    return rtrim($time, '0');
}

whats problem in this function?