SQL> select tablespace_name, initial_extent , next_extent 
  2  from dba_tablespaces;

TABLESPACE_NAME                INITIAL_EXTENT NEXT_EXTENT
------------------------------ -------------- -----------
EXAMPLE_SCH                            516096      516096
VOTER_DET                               65536

SQL> create table dumm1(n1 number)
  2  storage (initial 32K) tablespace voter_det;

SQL> select INITIAL_EXTENT from dba_tables
  2  where table_name='DUMM1';

INITIAL_EXTENT
--------------
         32768

SQL> select bytes from dba_extents
  2  where segment_name='DUMM1';

     BYTES
----------
     65536