convert seconds into mins hours in Oracle

select to_char(to_date(10000,'sssss'),'hh24:mi:ss') from dual;

or

SELECT 
    TO_CHAR(TRUNC(1000/3600),'FM9900') || ':' ||
    TO_CHAR(TRUNC(MOD(1000,3600)/60),'FM00') || ':' ||
    TO_CHAR(MOD(1000,60),'FM00')
FROM DUAL