91137785897 has 2 divisors, whose sum is σ = 91137785898. Its totient is φ = 91137785896.

The previous prime is 91137785839. The next prime is 91137786013. The reversal of 91137785897 is 79858773119.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 84994988521 + 6142797376 = 291539^2 + 78376^2 .

It is a cyclic number.

It is not a de Polignac number, because 91137785897 - 2⁶ = 91137785833 is a prime.

It is not a weakly prime, because it can be changed into another prime (91137785197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45568892948 + 45568892949.

It is an arithmetic number, because the mean of its divisors is an integer number (45568892949).

Almost surely, 2^91137785897 is an apocalyptic number.

It is an amenable number.

91137785897 is a deficient number, since it is larger than the sum of its proper divisors (1).

91137785897 is an equidigital number, since it uses as much as digits as its factorization.

91137785897 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26671680, while the sum is 65.

The spelling of 91137785897 in words is "ninety-one billion, one hundred thirty-seven million, seven hundred eighty-five thousand, eight hundred ninety-seven".