Name    Salary
SMITH    800

to 
Name         Salary
SMITH     EIGHT HUNDRED

SQL> select ename,
  2         sal,
  3         to_char(to_date(sal,'j'),'jsp') words
  4  from emp
  5  where deptno = 20;

ENAME             SAL WORDS
---------- ---------- -----------------------------------------------
SMITH            1600 one thousand six hundred
JONES            3775 three thousand seven hundred seventy-five
SCOTT            3800 three thousand eight hundred
ADAMS            1900 one thousand nine hundred
FORD             3800 three thousand eight hundred

SQL>

Select to_char(to_date(5373484,'j'),'jsp') words from dual;
five million three hundred seventy-three thousand four hundred eighty-four