<?php
$xml = simplexml_load_string("<xml><number>214748364800</number></xml>");
echo $xml->number . "\n"; // the proper number
$int = $xml->number / 1024 / 1024 / 1024; // initial cast to an int causes problems
echo $int . "\n";
$double = (double) $xml->number / 1024 / 1024 / 1024; // hard cast to a double fixes it
echo $double . "\n";
echo "214748364800" / 1024 / 1024 / 1024;
?>