even, composite, triangular, palindrome · 666th positive integer
The number 666
666 is an even composite number. It's known as the "number of the beast" in the Book of Revelation. It is the 666th positive integer.
Quick reference
| Prime factorization | 2 × 3 × 3 × 37 |
| Divisors | 1, 2, 3, 6, 9, 18, 37, 74, 111, 222, 333, 666 |
| Binary | 1010011010 |
| Hexadecimal | 0x29A |
| Roman numeral | DCLXVI |
| Digit sum | 18 |
| Properties | even, composite, triangular, palindrome |
Why 666 is notable
The "number of the beast" in the Book of Revelation.
Frequently asked
Is 666 a prime number?
No. 666 is composite. Its prime factorization is 2 × 3 × 3 × 37.
What are the factors of 666?
The factors (divisors) of 666 are 1, 2, 3, 6, 9, 18, 37, 74, 111, 222, 333, 666.
What is 666 in binary?
666 in binary is 1010011010. In hexadecimal it's 29A.
What is 666 as a Roman numeral?
666 in Roman numerals is DCLXVI.
What's the digit sum of 666?
Adding the digits of 666: 6 + 6 + 6 = 18.