Your translations are correct, it may be more common to say
¿Quién soy? instead of
¿Qué soy?, but it is more correct to say the latter phrase, since a number is a thing, and not a living being. It is obvious that a number would not speak, so it is fine to use which ever you feel more comfortable with, since using
¿Quién soy? would give more life to the number.
Quién usually refers to an animal, human or non-human. It is very similar to
Who in English.
Qué usually refers to an object, a thing. It is similar to
What in English.