666471857 has 4 divisors (see below), whose sum is σ = 667278576. Its totient is φ = 665665140.

The previous prime is 666471833. The next prime is 666471899. The reversal of 666471857 is 758174666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666471857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666471457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 402119 + ... + 403772.

It is an arithmetic number, because the mean of its divisors is an integer number (166819644).

Almost surely, 2^666471857 is an apocalyptic number.

It is an amenable number.

666471857 is a deficient number, since it is larger than the sum of its proper divisors (806719).

666471857 is an equidigital number, since it uses as much as digits as its factorization.

666471857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 806718.

The product of its digits is 1693440, while the sum is 50.

The square root of 666471857 is about 25816.1162261096. The cubic root of 666471857 is about 873.4953654871.

The spelling of 666471857 in words is "six hundred sixty-six million, four hundred seventy-one thousand, eight hundred fifty-seven".