Javascript Solution. Supports all integers from negative infinity to infinity:
var GetWord;
(function(){
GetWord = function (number) {
return (function f(number){
var output = [];
var is_negative = number < 0;
number = Math.abs(number);
var chunks = [];
for (var x = count_names.length - 1, limit = 0; x >= limit; --x) {
var chunk = Math.floor(number / counts[x]);
if (chunk !== 0) {
output.push(GetWord(chunk) + " " + count_names[x]);
}
chunks[x] = chunk;
number -= chunk * counts[x];
}
if (number !== 0) {
if (number <= 19) {
output.push(number_names[number]);
} else {
var tens = Math.floor(number / 10);
number -= tens * 10;
if (number === 0) {
output.push(number_names2[tens - 2]);
} else {
output.push(number_names2[tens - 2] + " " + GetWord(number));
}
}
}
if (output.length > 2) {
for (var x = 0, limit = output.length - 1; x < limit; ++x) {
output[x] += ","
}
}
if (output.length > 1) {
var ubound = output.length - 1;
output[output.length] = output[ubound];
output[ubound] = "and";
}
if (is_negative) {
output.splice(0, 0, "negative");
}
return output;
})(number).join(" ");
};
var number_names = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"];
var number_names2 = ["twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety", "hundred"]
var count_names = ["hundred", "thousand", "million", "billion", "trillion", "quadrillion", "quintillion", "sextillion", "septillion", "octillion", "nonillion", "decillion", "undecillion", "duodecillion", "tredecillion", "quattuordecillion", "quindecillion", "sexdecillion", "septendecillion", "octodecillion", "novemdecillion", "vigintillion"];
var counts = [100];
for (var x = counts.length, limit = count_names.length; x < limit; ++x) {
counts.push(Math.pow(1000, x));
}
})();
Application:
GetWord(1210); gives one thousand, two hundred, and ten
GetWord(2147483647); gives two billion, one hundred and forty seven million, four hundred and eighty three thousand, six hundred, and forty seven
GetWord(-123876124); gives negative one hundred and twenty three million, eight hundred and seventy six thousand, one hundred, and twenty four
If you need caps, just modify these array templates in the "capped" form.