I would like to say, 666 is only a bad number in Christian religion, and the spin offs of it. For example, the number 6 is very lucky in China, and 666 is an amazing number. People ask for at least one six to be in their license plate, phone number etc.
666 is also a smith number. 6+6+6 is 18. The prime factors of 666, 2, 3, 3, and 37, can be 2+3+3+3+7, which is also 18. I find the number interesting, being non religious myself.