Strictly speaking saying a single natural number is "computable" is a category error. Only functions can be computable or noncomputable. All other notions of co

Strictly speaking saying a single natural number is "computable" is a category error. Only functions can be computable or noncomputable. All other notions of computability must be reduced to a function on the natural numbers (e.g. recognition problems are shorthand for functions on the natural numbers that have a range of {0, 1}).