19115921009 has 2 divisors, whose sum is σ = 19115921010. Its totient is φ = 19115921008.

The previous prime is 19115920973. The next prime is 19115921021. The reversal of 19115921009 is 90012951191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9657385984 + 9458535025 = 98272^2 + 97255^2 .

It is an emirp because it is prime and its reverse (90012951191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19115921009 - 2²⁰ = 19114872433 is a prime.

It is not a weakly prime, because it can be changed into another prime (19115921309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9557960504 + 9557960505.

It is an arithmetic number, because the mean of its divisors is an integer number (9557960505).

Almost surely, 2^19115921009 is an apocalyptic number.

It is an amenable number.

19115921009 is a deficient number, since it is larger than the sum of its proper divisors (1).

19115921009 is an equidigital number, since it uses as much as digits as its factorization.

19115921009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7290, while the sum is 38.

The spelling of 19115921009 in words is "nineteen billion, one hundred fifteen million, nine hundred twenty-one thousand, nine".