Addition of Seconds with Date

I need help to add seconds to date & times.

(ie).. if the Date and Time is Dec 31, 2013 11:45:05 AM and if a add 173455 seconds to this date (173455 sec = 2 days, 10 min and 55 sec)

The result should be Jan 02, 2014 11:56:00. I try to use Time formula but i cant get it done.
In the same if i minus the value i need to get the date and time.

Note: I only use seconds to add / subtract..

Thanks in advance..

Dates are stored as a number where whole units are days. If you want to add seconds then divide them by 86400 (60 * 60 * 24) to get the duration in days.

=A1+(173455/(60*60*24))