There is three-way to find an Airtel mobile number you can use the USSD Code- By using USSD code you can easily visible your number on your device screen. You can use these codes 282# or *1211#.
Also, you can use Airtel Thanks App if on your mobile device you have installed the airtel thanks app then you can open it and on the home page, you can see your mobile number. If you are not installed then you can visit the play store and install the app and then check. for more information visit here: https://webslosh.com/how-to-check-your-airtel-number/