I CALCULATED RECENTLY that 26⁷ (in other words, 26 multiplied by itself seven times) is 8,031,810,176.

Which means that, as there are 26 letters in the alphabet, there would be enough combinations for everyone on the planet to be identified by a unique seven-letter word. With a couple of billion to spare, so you could weed out the rude ones.

Not all the words would be pronounceable, of course, but seven letters are much easier to remember than a string of meaningless numbers.