#!/usr/bin/perl -w
use strict;
use Number::Spell;
my $string=spell_number(8597);
print "$string\n";
-----
Result:
eight thousand five hundred ninety seven

##</code><code>##

  if($data=~/(\-?)\s*(\d+)/){

##</code><code>##

my $string=spell_number('1000000000000000'); #this works
my $string=spell_number(1000000000000000); #this doesNOT