Monitoring usage on Acrobat Pro

In the registry, Adobe Acrobat DC keeps track of the last time the application was started.  We intend to use this information to monitor actual usage of Acrobat Pro to determine whether an end user actually uses the Pro package.

The information is kept in a numerical format in HKEY_CURRENT_USER\Software\Adobe\Adobe Acrobat\DC\AVGeneral uLastAppLaunchTimeStamp and outputs something like '4260653704'

How can this number be calculated into a readable date/timestamp?