Unity Android Build bundle Id and alphanumeric company name

Since a company name can start with a number, the bundle id in the format:


will not be accepted and building the Android .apk fails.

Is there a particular reason why we can’t have numbers in the bundle id?

instead of writing your company name bundle id 123companyName.Appname
write it onetwothree.Company.AppName

because unity made it to where you have to use a string instead of an integer