Number to Word Converter

<?PHP
class numberConverter {
    protected $singles = array();
    protected $doubles = array();
    protected $triples = array();
    public function __construct() {
        $this->singles = array('one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve',
             'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventen', 'eighteen', 'nineteen');
        $this->doubles = array('twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety');
        $this->triples = array('hundred','thousand', 'million', 'billion', 'trillion');
    }
    public function convertNumber($number) {
        /*
            Splits the number into 3 digit sections
            Appends the correct prefix to that number
            Example:
                xxx,xxx,xxx
                (xxx) million (xxx) thousand (xxx)
        */
        $length = strlen($number); // number.length;
        $len = $length%3; // 7 digits split by 3 = 7%3 = 1 remaineder - the first digit is off
        $len = ($len==0)?3:$len; // 0 = 3;
        $pos = 0;
        $rounds = ceil($length/3); // Math.ceil
        $ret = "";
        for($i = 1;$i<=$rounds;$i++) {
            $nameIndex = $rounds-$i; // 3 rounds, first round, 3rd index "million"
            $thisThree = substr($number, $pos, $len);
            $ret .= $this->convertThree($thisThree);
            if($nameIndex >= 1 && $thisThree != 0) {
                $ret .= $this->triples[$nameIndex] . ' ';
            }
            $pos += $len;
            $len = 3;
        }
        return $ret;
    }
    private function convertThree($number) {
        /*
            Converts 3 digits at a time
            Example:
                123
                One hundred twenty three
        */
        $length = strlen($number); // Length of the number, typically three
        $pos = $length; // position
        $ret = ""; // return variable
        $lastTwo = substr($number, -2);// last two digits: 123 = 23; 23 = 23;
        for($i = 0;$i<$length;$i++) {
            $thisNumber = $number[$i]; // 1
            if($thisNumber != 0) {
                if($pos == 3) {
                    $ret .= $this->singles[$thisNumber-1] . ' ' . $this->triples[$pos-3] . ' '; // two hundred
                } else if($pos == 2 && $lastTwo <= 19 && $lastTwo >= 10) {
                    $ret .= $this->singles[$lastTwo-1] . ' '; // sixteen
                    break; // break the "for" loop
                } else if($pos == 2) {
                    $ret .= $this->doubles[$thisNumber-2] . ' '; // twenty, sixty
                } else {
                    $ret .= $this->singles[$thisNumber-1] . ' '; // three, four
                }
            }
            $pos--;
        }
        return $ret;
    }
}
$convert = new numberConverter();
echo $convert->convertNumber(1651613186); //1,651,613,186

<script type="text/javascript" rel="javascript">
    var singles = ['one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve',
        'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventen', 'eighteen', 'nineteen'];
    var doubles = ['twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety'];
    var triples = ['hundred','thousand', 'million', 'billion', 'trillion'];
    function convertNumber(number) {
        /*
            Splits the number into 3 digit sections
            Appends the correct prefix to that number
            Example:
                xxx,xxx
                (xxx) thousand (xxx)
        */
        var nameIndex,thisThree;
        number = String(number);
        var length = number.length;
        var len = length%3; // 7 digits split by 3 = 7%3 = 1 remaineder - the first digit is off
            len = (len==0)?3:len; // 0 = 3;
        var pos = 0;
        var rounds = Math.ceil(length/3);
        var ret = "";
        for(var i = 1;i<=rounds;i++) {
            nameIndex = rounds-i; // 3 rounds, first round, 3rd index "million"
            thisThree = number.substring(pos, len+pos);
            ret += convertThree(thisThree);
            if(nameIndex >= 1 && parseInt(thisThree) != 0) {
                ret += triples[nameIndex]+' ';
            }
            pos += len;
            len = 3;
        }
        return ret;
    }
    function convertThree(number) {
        /*
            Converts 3 digits at a time
            Example:
                123
                One hundred twenty three
        */
        number = number; // The number
        var thisNumber = 0;
        var length = number.length; // Length of the number, typically three
        var pos = length; // position
        var ret = ""; // return variable
        var lastTwo = parseInt(number.substring(number.length-2)); // last two digits: 123 = 23; 23 = 23;
        for(var i = 0;i<length;i++) {
            thisNumber = number[i]; // 1
            if(thisNumber != 0) {
                if(pos == 3) {
                    ret += singles[thisNumber-1] + ' ' + triples[pos-3]+' '; // two hundred
                } else if(pos == 2 && lastTwo <= 19 && lastTwo >= 10) {
                    ret += singles[lastTwo-1] + ' '; // sixteen
                    break; // break the "for" loop
                } else if(pos == 2) {
                    ret += doubles[thisNumber-2] + ' '; // twenty, sixty
                } else {
                    ret += singles[thisNumber-1] + ' '; // three, four
                }
            }
            pos--;
        }
        return ret;
    }
    alert(convertNumber(1651613186)); //1,651,613,186
</script>