If you still haven't found the number that you need, check your device or box.
Find the serial number with your Apple ID
On your iPhone, iPad or iPod touch with iOS 10.3 or later that's signed in with your Apple ID, go to Settings > [Your name]. Then Scroll down and tap your Apple TV to see the serial number.
If you don’t have an iPhone, iPad, or iPod touch that you use with your Apple TV, you can go to your Apple ID account page on your computer to find the serial number for your Apple TV. Just go to appleid.apple.com and sign in with the Apple ID that you use on the Apple TV. Then scroll down to the section called Devices, and select your Apple TV.
Find the serial number on other Apple products.
*Apple TV 4K and Apple TV (4th generation) ships with the same remote everywhere. In countries and regions that support Siri, the remote is called Siri Remote. Elsewhere, it’s called Apple TV Remote. Siri works on either remote as long as your Apple TV 4K or Apple TV (4th generation) is set up with a language and country or region that supports Siri.