The only problem here is memorizing this password. Assuming you don’t have a photographic memory, you’d have to spend time drilling these characters into your brain. There are random password generators that can come up with this type of password for you — they’re generally most useful as part of a password manager that will also remember them for you.
You’ll need to think about how to come up with a memorable password. You don’t want to use something obvious with dictionary characters, so consider using some sort of trick to memorize it.
For example, maybe you can find it easy to remember a sentence like “The first house I ever lived in was 613 Fake Street. Rent was $400 per month.” You can then turn that into a password by using the first digits of each word, so your password would become TfhIeliw613FS.Rw$4pm. This is a strong password at 21 digits. Sure, a true random password might include a few more numbers and symbols and upper-case letters scrambled around, but it’s not bad at all. You just need to remember two simple sentences, so it’s easy to remember.