666656667 has 24 divisors (see below), whose sum is σ = 1014773760. Its totient is φ = 420571440.

The previous prime is 666656663. The next prime is 666656677. The reversal of 666656667 is 766656666.

It is a happy number.

It is not a de Polignac number, because 666656667 - 2² = 666656663 is a prime.

It is a super-2 number, since 2×666656667² = 888862223311097778, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (666656663) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 208918 + ... + 212084.

It is an arithmetic number, because the mean of its divisors is an integer number (42282240).

Almost surely, 2^666656667 is an apocalyptic number.

666656667 is a deficient number, since it is larger than the sum of its proper divisors (348117093).

666656667 is a wasteful number, since it uses less digits than its factorization.

666656667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4423 (or 4420 counting only the distinct ones).

The product of its digits is 9797760, while the sum is 54.

The square root of 666656667 is about 25819.6953312776. The cubic root of 666656667 is about 873.5760969577.

Subtracting 666656667 from its reverse (766656666), we obtain a palindrome (99999999).

The spelling of 666656667 in words is "six hundred sixty-six million, six hundred fifty-six thousand, six hundred sixty-seven".