666643112720 has 80 divisors (see below), whose sum is σ = 1678394211312. Its totient is φ = 244785162240.

The previous prime is 666643112719. The next prime is 666643112783. The reversal of 666643112720 is 27211346666.

It can be written as a sum of positive squares in 8 ways, for example, as 261984280336 + 404658832384 = 511844^2 + 636128^2 .

It is a tau number, because it is divible by the number of its divisors (80).

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, 1582487 + ... + 1958966.

Almost surely, 2^666643112720 is an apocalyptic number.

It is an amenable number.

666643112720 is an abundant number, since it is smaller than the sum of its proper divisors (1011751098592).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666643112720 is a wasteful number, since it uses less digits than its factorization.

666643112720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3541660 (or 3541654 counting only the distinct ones).

The product of its (nonzero) digits is 435456, while the sum is 44.

The spelling of 666643112720 in words is "six hundred sixty-six billion, six hundred forty-three million, one hundred twelve thousand, seven hundred twenty".