Prashant, the answer is absolutely correct, there is no native way to spell in words a number value for another languages to an Oracle database, you will need to write something.... Two main possibilities exist for this :
a) via character functions or calculations find the decimal, hundreds, thousands, etc, for the number and inside a nest of IFs append the correct words in a string : for example,
http://www.orafaq.com/node/1448 do this for Indian numeric system,
http://www.profissionaloracle.com.br/gpo/artigo/programacao/470-numero-por-extenso-monetario-e-calculo-de-formulas-matematicas-no-oracle and
http://lib.seven.com.br/imprimir_artigo.asp?codartigo=976 do the same for Portuguese numeric system (I did things like this many times in Brazilian customers)... You could take one of these as a basis, translating the number grouping names to Spanish
OR
b) use the JSP trick : since a long time, the JSP format mask in some Oracle convertion built-ins give to you a number value spelled in words (but in Englis only) : you cold use this and just replace the English number grouping names to Spanish,
https://community.oracle.com/message/454870#454870 does Exactly That...
This would be the easier option, I think...
Regards,
J. Laurindo Chiappa