19645503791 has 2 divisors, whose sum is σ = 19645503792. Its totient is φ = 19645503790.

The previous prime is 19645503767. The next prime is 19645503809. The reversal of 19645503791 is 19730554691.

It is a strong prime.

It is an emirp because it is prime and its reverse (19730554691) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19645503791 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19645503191) 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, 9822751895 + 9822751896.

It is an arithmetic number, because the mean of its divisors is an integer number (9822751896).

Almost surely, 2^19645503791 is an apocalyptic number.

19645503791 is a deficient number, since it is larger than the sum of its proper divisors (1).

19645503791 is an equidigital number, since it uses as much as digits as its factorization.

19645503791 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1020600, while the sum is 50.

The spelling of 19645503791 in words is "nineteen billion, six hundred forty-five million, five hundred three thousand, seven hundred ninety-one".