zlacker

    def digitlength(n):
        digits = 1
        while (n > 9):
            digits += 1
            n /= 10
        return digits

Also may want to set n = abs(n) in the beginning, in case n is negative.

>>a-niko+(OP)
The problem statement said that the input would be natural numbers.

>>gnuvin+5
Wait, do natural numbers include zero? evil grin

>>lifthr+M6
No support for that in Sloane's. https://oeis.org/A000027

>>lifthr+M6
I looked up wikipedia which says there's no conclusive definition.

>>chopin+JH
The joke is that, if you don't need to check if the input is negative because it is not a natural number, you can also choose a definition of the natural number without zero to avoid special casing it at all.