select to_date('01/01/1970','mm/dd/yyyy') + numtodsinterval(1456342438,'SECOND'),
TRUNC(to_date('01/01/1970','mm/dd/yyyy') + numtodsinterval(1456342438,'SECOND')) from dual;
Isso funcionou.
select to_date('01/01/1970','mm/dd/yyyy') + numtodsinterval(1456342438,'SECOND'),
TRUNC(to_date('01/01/1970','mm/dd/yyyy') + numtodsinterval(1456342438,'SECOND')) from dual;