91749493257 has 4 divisors (see below), whose sum is σ = 122332657680. Its totient is φ = 61166328836.

The previous prime is 91749493247. The next prime is 91749493267. The reversal of 91749493257 is 75239494719.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75239494719 = 3 ⋅25079831573.

It is an interprime number because it is at equal distance from previous prime (91749493247) and next prime (91749493267).

It is a cyclic number.

It is not a de Polignac number, because 91749493257 - 2²³ = 91741104649 is a prime.

It is a super-3 number, since 3×91749493257³ (a number of 34 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 91749493257.

It is not an unprimeable number, because it can be changed into a prime (91749493247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15291582207 + ... + 15291582212.

It is an arithmetic number, because the mean of its divisors is an integer number (30583164420).

Almost surely, 2^91749493257 is an apocalyptic number.

It is an amenable number.

91749493257 is a deficient number, since it is larger than the sum of its proper divisors (30583164423).

91749493257 is a wasteful number, since it uses less digits than its factorization.

91749493257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30583164422.

The product of its digits is 17146080, while the sum is 60.

The spelling of 91749493257 in words is "ninety-one billion, seven hundred forty-nine million, four hundred ninety-three thousand, two hundred fifty-seven".