[zeveb]

With mixed-case letters and digits, all you need are 22 characters.

A 128-bit security margin is considered good enough currently; a 62-character alphabet (26 lowercase, 26 uppercase, 10 digits) provides 5.95 potential bits of entropy per character; thus a 21.50-character password would provide 128 bits. You can't have a fractional character, so … 22 characters.

Typing 'tgcSq08O2fEZ5hcZk3Gvgk' in from a screen is easy enough, although not something I'd want to do every day.