SQL> create table test (col number(38));

Table created.

SQL> insert into test values (56465464654654654654);

1 row created.

SQL> select * From test;

       COL
----------
5,6465E+19

SQL> column col format 999999999999999999999999999999999
SQL> select * From test;

                               COL
----------------------------------
              56465464654654654654

SQL> set numformat 9999999999999999999999999
SQL> select * From test;

                       COL
--------------------------
      56465464654654654654

SQL> set numwidth 25
SQL> select * From test;

                      COL
-------------------------
     56465464654654654654