With phone numbers and words I see them whole in my mind. But probably this is true for most, no?
Hmm, I remember phone numbers physically -- meaning I automatically memorize their spatial orientation on a typical phone pad. Sometimes to write them, I move my fingers and pretend to dial... or visualize myself dialing.

I suppose it's related to being able to return to anywhere I've ever been, but having no idea of any of the street names.
I would also remember strings of numbers by mentally repeating and "locking" them in, not by visualizing. And, I'm a great speller, but would never picture a whole word... if needed, I would write it in my mind one letter at a time.