Google has gotten my phone number?

I use google docs through a gmail account under a fake name and it always asks if I want to add a phone number "for security" and I always say "no". Well, today it had my number and will not allow me to sign in without receiving a text? *How* did it get my number in the first place and is there any way I can go back to just using my fake name/fake email + password??

google phone phone number privacy