9978261791 has 2 divisors, whose sum is σ = 9978261792. Its totient is φ = 9978261790.

The previous prime is 9978261767. The next prime is 9978261841. The reversal of 9978261791 is 1971628799.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 9978261791 - 2¹⁰ = 9978260767 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 9978261791.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9978261191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4989130895 + 4989130896.

It is an arithmetic number, because the mean of its divisors is an integer number (4989130896).

Almost surely, 2^9978261791 is an apocalyptic number.

9978261791 is a deficient number, since it is larger than the sum of its proper divisors (1).

9978261791 is an equidigital number, since it uses as much as digits as its factorization.

9978261791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3429216, while the sum is 59.

The square root of 9978261791 is about 99891.2498219939. The cubic root of 9978261791 is about 2152.8724390809.

The spelling of 9978261791 in words is "nine billion, nine hundred seventy-eight million, two hundred sixty-one thousand, seven hundred ninety-one".