Algorithm: Convert number to word

This time another algorithm, converting a number to word. Try typing in a number below:
The algorithm in Javascript below. Click here for C# gist.
NumberToWords= function(number)
            {

                if (number == 0)
                    return "zero";

                if (number < 0)
                    return "minus " + $scope.NumberToWords(Math.abs(number));

                var words = "";

                if (Math.floor(number / 1000000) > 0)
                {
                    words += $scope.NumberToWords(Math.floor(number / 1000000)) + " million ";
                    number %= 1000000;
                }

                if (Math.floor(number / 1000) > 0)
                {
                    words += $scope.NumberToWords(Math.floor(number / 1000)) + " thousand ";
                    number %= 1000;
                }

                if (Math.floor(number / 100) > 0)
                {
                    words += $scope.NumberToWords(Math.floor(number / 100)) + " hundred ";
                    number %= 100;
                }

                if (number > 0)
                {
                    if (words != "")
                        words += "and ";

                    var unitsMap = [ "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" ];
                    var tensMap = ["zero", "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety" ];

                    if (number < 20)
                        words += unitsMap[number];
                    else
                    {
                        words += tensMap[Math.floor(number / 10)];
                        if ((number % 10) > 0)
                            words += "-" + unitsMap[number % 10];
                    }
                }



                return words;
            }