SQL & PL/SQL

I am migrating sql server to oracle ( my version is 11g)

in sql server

------------ --> statement 1

select FLOOR(Convert(Float, current_timestamp));

----------------------

41812 (1 row(s) affected)

-- statement2

SELECT CONVERT(DateTime, FLOOR(Convert(Float, current_timestamp)))

-----------------------

2014-06-24 00:00:00.000 (1 row(s) affected)

In oracle I migrated statement1 as below

select FLOOR(TRUNC(systimestamp) - TO_DATE('01-01-1900 00:00:00', 'DD-MM-YYYY HH24:MI:SS')) from dual;

FLOOR(TRUNC(SYSTIMESTAMP)-TO_DATE('01-01-190000:00:00','DD-MM-YYYYHH24:MI:SS'))

-------------------------------------------------------------------------------                                                                         

41812 

But, don't know how to convert this value to timestamp in oracle. Please help