666646671 has 4 divisors (see below), whose sum is σ = 888862232. Its totient is φ = 444431112.

The previous prime is 666646627. The next prime is 666646679. The reversal of 666646671 is 176646666.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 666646671 - 2⁹ = 666646159 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666646671.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666646679) 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, 111107776 + ... + 111107781.

It is an arithmetic number, because the mean of its divisors is an integer number (222215558).

Almost surely, 2^666646671 is an apocalyptic number.

666646671 is a deficient number, since it is larger than the sum of its proper divisors (222215561).

666646671 is a wasteful number, since it uses less digits than its factorization.

666646671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222215560.

The product of its digits is 1306368, while the sum is 48.

The square root of 666646671 is about 25819.5017573926. The cubic root of 666646671 is about 873.5717307371.

The spelling of 666646671 in words is "six hundred sixty-six million, six hundred forty-six thousand, six hundred seventy-one".