9978998791 has 2 divisors, whose sum is σ = 9978998792. Its totient is φ = 9978998790.

The previous prime is 9978998761. The next prime is 9978998831. The reversal of 9978998791 is 1978998799.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (1978998799) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9978998791 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9978998761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4989499395 + 4989499396.

It is an arithmetic number, because the mean of its divisors is an integer number (4989499396).

Almost surely, 2^9978998791 is an apocalyptic number.

9978998791 is a deficient number, since it is larger than the sum of its proper divisors (1).

9978998791 is an equidigital number, since it uses as much as digits as its factorization.

9978998791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 185177664, while the sum is 76.

The square root of 9978998791 is about 99894.9387656852. The cubic root of 9978998791 is about 2152.9254418970.

The spelling of 9978998791 in words is "nine billion, nine hundred seventy-eight million, nine hundred ninety-eight thousand, seven hundred ninety-one".