91857257 has 2 divisors, whose sum is σ = 91857258. Its totient is φ = 91857256.

The previous prime is 91857169. The next prime is 91857263. The reversal of 91857257 is 75275819.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81288256 + 10569001 = 9016^2 + 3251^2 .

It is an emirp because it is prime and its reverse (75275819) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 91857257 - 2²⁰ = 90808681 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (91857757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45928628 + 45928629.

It is an arithmetic number, because the mean of its divisors is an integer number (45928629).

Almost surely, 2^91857257 is an apocalyptic number.

It is an amenable number.

91857257 is a deficient number, since it is larger than the sum of its proper divisors (1).

91857257 is an equidigital number, since it uses as much as digits as its factorization.

91857257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 176400, while the sum is 44.

The square root of 91857257 is about 9584.2191648564. The cubic root of 91857257 is about 451.2021469962.

The spelling of 91857257 in words is "ninety-one million, eight hundred fifty-seven thousand, two hundred fifty-seven".