Access to apple id account
If you need access to your account, and you don't know the former number nor do you have access to any Apple devices that your Apple ID is signed into (iPhone, iPad, iPod, or Mac) then you cannot recover your account. Account recovery requires no less than the associated Apple ID email and the phone number associated with the account &amp; devices that had access to the account.

Apple's automated ID system can only verify your account with passwords, devices &amp; phone numbers. Emails arent a secure way of identification so they no longer use them to verify you with two-factor identification. 

What I would do is backtrack the previous carriers or phone numbers you've used lately. Start with your current carrier and work backwards. If you've ever had your phone number ported over from one carrier to another you need to call the carrier that brought over your number and have them provide you with it.

If you can at least find the phone number, but don't have access to it, then you can go through what's called Account Recovery. Just go to iforgot.apple.com and enter your Apple ID email address then the phone number on the next page and it will make you go through a waiting process to verify your accounts security (checking for active devices, breaches, etc.)

If you manage to find the number. Comment here because I can explain the recovery process in detail since most people end up waiting longer than expected.