Convert a number to equivalent string representation

NumberToString.lua

NumberToString = (function ()
    local insert, concat, floor, abs = table.insert, table.concat, math.floor, math.abs
    local num, tens, bases = {
        'one',
        'two',
        'three',
        'four',
        'five',
        'six',
        'seven',
        'eight',
        'nine',
        'ten',
        'eleven',
        'twelve',
        'thirteen',
        'fourteen',
        'fifteen',
        'sixteen',
        'seventeen',
        'eighteen',
        'nineteen'
    }, {
        [2] = 'twenty',
        [3] = 'thirty',
        [4] = 'forty',
        [5] = 'fifty',
        [6] = 'sixty',
        [7] = 'seventy',
        [8] = 'eighty',
        [9] = 'ninety',
    }, {
        { 10^12, ' trillion' },
        { 10^9, ' billion' },
        { 10^6, ' million' },
        { 10^3, ' thousand' },
        { 10^2, ' hundred' },
    }
    return function(n, pretty)
        if pretty == nil then
            pretty = true
        end
        local str = {}
        if n < 0 then
            insert( str, "minus" )
        elseif n == 0 then
            return "zero"
        end
        n = floor( abs(n) )
        if n > 10^15 then
            insert( str, "infinity" )
        else
            local AND
            for _, base in ipairs(bases) do
                local value = base[1]
                if n >= value then
                    insert( str, NumberToString(n / value)..base[2] )
                    n, AND = n % value, pretty
                end
            end
            if n > 0 then
                if AND then
                    insert( str, "and" )
                end
                insert( str, num[n] or tens[floor(n/10)]..(n % 10 > 0 and '-'..num[n % 10] or '') )
            end
        end
        return concat(str, ' ')
    end
end)()

NumberToString.py

from math import *

num, tens, bases = [
        '',
        'one',
        'two',
        'three',
        'four',
        'five',
        'six',
        'seven',
        'eight',
        'nine',
        'ten',
        'eleven',
        'twelve',
        'thirteen',
        'fourteen',
        'fifteen',
        'sixteen',
        'seventeen',
        'eighteen',
        'nineteen',
        'twenty'
    ], [
        '',
        '',
        '',
        'thirty',
        'forty',
        'fifty',
        'sixty',
        'seventy',
        'eighty',
        'ninety',
    ], [
        (10**12, ' trillion'),
        (10**9, ' billion'),
        (10**6, ' million'),
        (10**3, ' thousand'),
        (10**2, ' hundred')
    ]
t = len(num)
def NumberToString(n):
    n, s = int( floor(abs(n)) ), ()
    if n <= t:
        return num[n]
    for i in bases:
        if n >= i[0]:
            x = NumberToString(n / i[0])
            s += ( x + i[1], )
            n = int( n % i[0] )
    if n <= t:
        s += ( num[n], )
    else:
        s += ( tens[int(floor(n / 10))] + ' ' + num[n % 10], )
    return ' '.join(s)