19111717921 has 2 divisors, whose sum is σ = 19111717922. Its totient is φ = 19111717920.

The previous prime is 19111717913. The next prime is 19111717931. The reversal of 19111717921 is 12971711191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11628602896 + 7483115025 = 107836^2 + 86505^2 .

It is a cyclic number.

It is not a de Polignac number, because 19111717921 - 2³ = 19111717913 is a prime.

It is not a weakly prime, because it can be changed into another prime (19111717931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9555858960 + 9555858961.

It is an arithmetic number, because the mean of its divisors is an integer number (9555858961).

Almost surely, 2^19111717921 is an apocalyptic number.

It is an amenable number.

19111717921 is a deficient number, since it is larger than the sum of its proper divisors (1).

19111717921 is an equidigital number, since it uses as much as digits as its factorization.

19111717921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7938, while the sum is 40.

The spelling of 19111717921 in words is "nineteen billion, one hundred eleven million, seven hundred seventeen thousand, nine hundred twenty-one".