19997816879 has 2 divisors, whose sum is σ = 19997816880. Its totient is φ = 19997816878.

The previous prime is 19997816849. The next prime is 19997816933. The reversal of 19997816879 is 97861879991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19997816879 - 2⁸ = 19997816623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19997816809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9998908439 + 9998908440.

It is an arithmetic number, because the mean of its divisors is an integer number (9998908440).

Almost surely, 2^19997816879 is an apocalyptic number.

19997816879 is a deficient number, since it is larger than the sum of its proper divisors (1).

19997816879 is an equidigital number, since it uses as much as digits as its factorization.

19997816879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 123451776, while the sum is 74.

The spelling of 19997816879 in words is "nineteen billion, nine hundred ninety-seven million, eight hundred sixteen thousand, eight hundred seventy-nine".