When backing up your mnemonic phrase, we strongly recommend utilizing physical media, which include producing about the mnemonic phrase card or possibly a metallic board such as the SafePal Cypher. You can also retain a number of back-ups of it. Standard recovery phrases use a selected list of 2048 words http://edgargvkh682.theburnward.com/from-mnemonics-to-security-understanding-bip39-passphrases-and-their-importance-in-copyright