Is it illegal not to have a name?

No, but it's very inconvenient.

And if u tell people u don't have a name then u might still get arrested.

do u want a number instead?

No
Its a good deterrent against the deathnote after all

I have no idea... I have never really thought about it before.

Nope, because it´s like if u didn´t existed.

Yes

Kind of awkward but I don't think it's illegal.

I've never thought about that...but it probably is. If u think about it, don't u always have a name because how will people address you? Unless u don't live near people and aren't aware of yourself.