19866633817 has 2 divisors, whose sum is σ = 19866633818. Its totient is φ = 19866633816.

The previous prime is 19866633767. The next prime is 19866633821. The reversal of 19866633817 is 71833666891.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15171095241 + 4695538576 = 123171^2 + 68524^2 .

It is a cyclic number.

It is not a de Polignac number, because 19866633817 - 2¹¹ = 19866631769 is a prime.

It is not a weakly prime, because it can be changed into another prime (19866633827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9933316908 + 9933316909.

It is an arithmetic number, because the mean of its divisors is an integer number (9933316909).

Almost surely, 2^19866633817 is an apocalyptic number.

It is an amenable number.

19866633817 is a deficient number, since it is larger than the sum of its proper divisors (1).

19866633817 is an equidigital number, since it uses as much as digits as its factorization.

19866633817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7838208, while the sum is 58.

The spelling of 19866633817 in words is "nineteen billion, eight hundred sixty-six million, six hundred thirty-three thousand, eight hundred seventeen".