There has been a lot of speculation that the number 666 came from the name of Nero.
During his era, coins were minted in the eastern part of the roman empire with the words in the Hebrew script of the Greek words Neron Kaiser (Emperor Nero).
If we consider not the letters themselves, but their numerical values, their sum equals 666. In favour of this, a fragment of a verse found on the Oxyrhynchus site states the devil's number is 616.
If we take the Nero Caeser spelling as the basis, the sum of the numerical values is reduced by 50 and equals 616, that is, Irenaeus took an erroneous spelling.
In addition, when multiplied by 6,666, this number becomes infinity. Many interpret this infinity as God's perfection and power. When compared to God's perfect creation, humans, the devil's handiwork appears to be lacking.