Need help converting cell contents from seconds to a date and time. File was exported from Active Directory into a CSV file. Other date fields display date and time, i.e. 20041029043416.0Z. All of the cells in the column for last logon displays an exponential number i.e. 1.27771E+17. When this cell is accessed with mouse or when copied and pasted, 127770982728624000 is displayed. After searching the Internet on converting seconds to date, I found this formula but am not sure how to use it on the cells in the column for last logon.
Set cell format to:
Date, type = y/m/yy hh:mm
Set cell function to:
=unixdatetime /(60*60*24)+DATE(1970,1,1)
This will retun date and time

I would appreciate a step by step process on how to convert seconds to date and time using the example: 127770982728624000.
Thanks in advance for your assistance.