666639985 has 16 divisors (see below), whose sum is σ = 918624960. Its totient is φ = 459311040.

The previous prime is 666639979. The next prime is 666640001. The reversal of 666639985 is 589936666.

It is a happy number.

It is not a de Polignac number, because 666639985 - 2⁹ = 666639473 is a prime.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 317922 + ... + 320011.

It is an arithmetic number, because the mean of its divisors is an integer number (57414060).

Almost surely, 2^666639985 is an apocalyptic number.

It is an amenable number.

666639985 is a deficient number, since it is larger than the sum of its proper divisors (251984975).

666639985 is a wasteful number, since it uses less digits than its factorization.

666639985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 637968.

The product of its digits is 12597120, while the sum is 58.

The square root of 666639985 is about 25819.3722812930. The cubic root of 666639985 is about 873.5688102894.

The spelling of 666639985 in words is "six hundred sixty-six million, six hundred thirty-nine thousand, nine hundred eighty-five".