19866644457 has 16 divisors (see below), whose sum is σ = 28933232832. Its totient is φ = 12025267520.

The previous prime is 19866644453. The next prime is 19866644459. The reversal of 19866644457 is 75444666891.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 19866644457 - 2² = 19866644453 is a prime.

It is a Smith number, since the sum of its digits (60) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 19866644457.

It is not an unprimeable number, because it can be changed into a prime (19866644453) 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 15 ways as a sum of consecutive naturals, for example, 351378 + ... + 403979.

It is an arithmetic number, because the mean of its divisors is an integer number (1808327052).

Almost surely, 2^19866644457 is an apocalyptic number.

It is an amenable number.

19866644457 is a deficient number, since it is larger than the sum of its proper divisors (9066588375).

19866644457 is a wasteful number, since it uses less digits than its factorization.

19866644457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 756168.

The product of its digits is 34836480, while the sum is 60.

The spelling of 19866644457 in words is "nineteen billion, eight hundred sixty-six million, six hundred forty-four thousand, four hundred fifty-seven".