Try the following:
$ nslookup github.com
[...]
Non-authoritative answer:
Name: github.com
Address: 140.82.121.3
See also the completely ignored post in their forums.
No the number is public. The IPv4 addresses allocated to the US are about 1.524 Billion, and there are ~332 million people in the US. Most of those IPv4 addresses are allocated to servers in datacenters, but individual people having a public IP for their house is really common. Yeah, your devices are behind NAT, but you can get one. To their point, in countries like India, people outnumber IPv4 addresses so much this isn’t possible. Just getting people there online in a way they can interact with the IPv4 Internet is tricky to do well.