19440509917 has 2 divisors, whose sum is σ = 19440509918. Its totient is φ = 19440509916.

The previous prime is 19440509911. The next prime is 19440509941. The reversal of 19440509917 is 71990504491.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18734491876 + 706018041 = 136874^2 + 26571^2 .

It is an emirp because it is prime and its reverse (71990504491) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19440509917 - 2²³ = 19432121309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19440509911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9720254958 + 9720254959.

It is an arithmetic number, because the mean of its divisors is an integer number (9720254959).

Almost surely, 2^19440509917 is an apocalyptic number.

It is an amenable number.

19440509917 is a deficient number, since it is larger than the sum of its proper divisors (1).

19440509917 is an equidigital number, since it uses as much as digits as its factorization.

19440509917 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 408240, while the sum is 49.

The spelling of 19440509917 in words is "nineteen billion, four hundred forty million, five hundred nine thousand, nine hundred seventeen".