91523521 has 4 divisors (see below), whose sum is σ = 93755844. Its totient is φ = 89291200.

The previous prime is 91523503. The next prime is 91523539. The reversal of 91523521 is 12532519.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12532519 = 17 ⋅737207.

It is an interprime number because it is at equal distance from previous prime (91523503) and next prime (91523539).

It can be written as a sum of positive squares in 2 ways, for example, as 30371121 + 61152400 = 5511^2 + 7820^2 .

It is a cyclic number.

It is not a de Polignac number, because 91523521 - 2⁵ = 91523489 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 91523521.

It is not an unprimeable number, because it can be changed into a prime (91523591) 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, 1116100 + ... + 1116181.

It is an arithmetic number, because the mean of its divisors is an integer number (23438961).

Almost surely, 2^91523521 is an apocalyptic number.

It is an amenable number.

91523521 is a deficient number, since it is larger than the sum of its proper divisors (2232323).

91523521 is a wasteful number, since it uses less digits than its factorization.

91523521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2232322.

The product of its digits is 2700, while the sum is 28.

The square root of 91523521 is about 9566.7926182185. The cubic root of 91523521 is about 450.6550476558.

The spelling of 91523521 in words is "ninety-one million, five hundred twenty-three thousand, five hundred twenty-one".