Another point on the 666 number

2/3 is the ratio of the fifth interval in music, all those heavy metal bands used exclusively fifth chords or power chords, for the most part, there are lots of exceptions, of course. For non-musicians, there's nothing inherently bad about the interval, actually the flatted fifth, a half-step down, was called the Devil's interval, it's dissonant but very useful as a passing tone.