666880661 has 8 divisors (see below), whose sum is σ = 669496320. Its totient is φ = 664270992.

The previous prime is 666880651. The next prime is 666880663. The reversal of 666880661 is 166088666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 666880661 - 2¹⁸ = 666618517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666880663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 398735 + ... + 400403.

It is an arithmetic number, because the mean of its divisors is an integer number (83687040).

Almost surely, 2^666880661 is an apocalyptic number.

It is an amenable number.

666880661 is a deficient number, since it is larger than the sum of its proper divisors (2615659).

666880661 is a wasteful number, since it uses less digits than its factorization.

666880661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2995.

The product of its (nonzero) digits is 497664, while the sum is 47.

The square root of 666880661 is about 25824.0326246696. The cubic root of 666880661 is about 873.6739253716.

The spelling of 666880661 in words is "six hundred sixty-six million, eight hundred eighty thousand, six hundred sixty-one".