I have a very bad neighbor! I have to use these captured files in an ongoing court issue with him shooting my animals with a pellet rifle. I would like to convert the files names from say 1617045279541 to something readable like 2021.03.29.17.30.19 which is year 2021, month of march, 29th day 17 hour 30th minute, and 19 seconds. I would love to have a bash rename string to automatically perform this task so I can set it up in Cron to change the name of the file, modify the file creation and modification to the same value. Thank you in advance. I'm running ubuntu 20.04.2 LTS.

date -d @1617045279541
Wed 15 Feb 53212 03:19:01 PM EST

This is the incorrect result

Get rid of the last 3 digits.

Are these audio or video files you are capturing of your neighbor? What utility are you using to 'capture' them?

Edit: I see you are using an 'Arlo' camera, had to look it up.