The following SQL statement tries to format a large number with apostrophes as thousands-separator. It throws a ORA-01481: invalid number format model error:
select
to_char(123456789.01234, '999''999''999.00')
from
dual;
This SQL statement uses an explicit nls_numeric_characters value so that the number is formatted as desired:
select
to_char(123456789.01234, '999g999g999d00', q'[nls_numeric_characters='.'']')
from
dual;