[infogulch]

If we're in a database context you could store the length of the number in another number (64 bit would be plenty, nobody is storing a number with 18 exabytes of digits) then compare/sort by that first then the number itself, bases are irrelevant, besides the space savings of storing it directly in binary.

In fact I'd make an index on (len(N), N), then include len(X) and X in all your comparisons and range queries (wrapping for ergonomics as needed). You can use any base storage (including compact varbinary base256).