Finding Serial Number

I have an ipad mini from 2014 which has been stolen. The device is not showing on my device list anymore because I had logged it out from my Apple ID a few days ago when updating my password. Does any one know how I can recover the serial number of the device?

I have registered it to my name on Apple's website when I bought it back in 2014. I do no longer have its package.

I need the serial number to report the theft to the police.

Thanks a lot for your help.