Convert unix timestamp to date in excel / libreoffice calc

Convert from Epoch Unix Timestamp format milliseconds to readable date (human date).

From format seconds:

=(D2/86400)+DATE(1970,1,1)

From format milliseconds:

=(D2/86400000)+DATE(1970,1,1)

And format cell to a new format:

 

References:

- https://unixtime.org/

- https://www.unixtimestamp.com/