Please download and install
http://extensions.libreoffice.org/extension-center/numbertext-1
I needed to format a number to written (long-hand) for a check. This did produce what was needed.
When using MONEYTEXT(), reference your cell with the number in it. Although the command asks for more, it is not required. It appears to format from the default languages settings.
Make sure your language settings are correct.
I did not test NUMBERTEXT, also within this extension.
Hope this helps.
Paul