Question: Can you brand a company using numbers? Answer: Affirmative. Numbers are strong symbols that we can understand without having to read an actual word. You write for example "1" and your mind automatically reads "one". This is a strong asset in a world that's full speed ahead and the time to read and memorize things is very tight.
I've researched a handful of logo designs that use numbers as their main design asset and I've noticed several elements and strong points that designers use with their number logo designs.
Numbers transmit more than their primary meaning. The meaning of "1" goes beyond the primary understanding of singularity; it also means "the first", "the best", being the ultimate superlative if you want.
Numbers can replace words, speeds up the reading and compresses the space use to write a phrase. For example one can easily replace "To Go" with "2Go", the latter being shorter and more appealing visually.
Numbers can function as graphical elements and they can replace icons or letters. Take for example 99designs logo listed below that uses an inversed number 9 instead of the "d" letter and another lowered number 9 instead of the "g" letter. Also you can analyze the Six Locks logo design where number 6 functions as a lock icon.
Numbers can function as a powerful design tool. When used smartly they ca impress and make the logo memorable. They are symbols that we grow with from infancy and they can easily transmit a message beyond words and even languages.