91787878397 has 2 divisors, whose sum is σ = 91787878398. Its totient is φ = 91787878396.

The previous prime is 91787878387. The next prime is 91787878421. The reversal of 91787878397 is 79387878719.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55140902041 + 36646976356 = 234821^2 + 191434^2 .

It is an emirp because it is prime and its reverse (79387878719) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91787878397 - 2²⁶ = 91720769533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91787878387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45893939198 + 45893939199.

It is an arithmetic number, because the mean of its divisors is an integer number (45893939199).

Almost surely, 2^91787878397 is an apocalyptic number.

It is an amenable number.

91787878397 is a deficient number, since it is larger than the sum of its proper divisors (1).

91787878397 is an equidigital number, since it uses as much as digits as its factorization.

91787878397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 298722816, while the sum is 74.

The spelling of 91787878397 in words is "ninety-one billion, seven hundred eighty-seven million, eight hundred seventy-eight thousand, three hundred ninety-seven".