19619819591 has 2 divisors, whose sum is σ = 19619819592. Its totient is φ = 19619819590.

The previous prime is 19619819581. The next prime is 19619819641. The reversal of 19619819591 is 19591891691.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19619819591 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19619819591.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19619819581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9809909795 + 9809909796.

It is an arithmetic number, because the mean of its divisors is an integer number (9809909796).

Almost surely, 2^19619819591 is an apocalyptic number.

19619819591 is a deficient number, since it is larger than the sum of its proper divisors (1).

19619819591 is an equidigital number, since it uses as much as digits as its factorization.

19619819591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1574640, while the sum is 59.

The spelling of 19619819591 in words is "nineteen billion, six hundred nineteen million, eight hundred nineteen thousand, five hundred ninety-one".