91230991 has 4 divisors (see below), whose sum is σ = 91250584. Its totient is φ = 91211400.

The previous prime is 91230961. The next prime is 91231009. The reversal of 91230991 is 19903219.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19903219 = 7 ⋅2843317.

It is a cyclic number.

It is not a de Polignac number, because 91230991 - 2⁹ = 91230479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91230961) 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, 1636 + ... + 13606.

It is an arithmetic number, because the mean of its divisors is an integer number (22812646).

Almost surely, 2^91230991 is an apocalyptic number.

91230991 is a deficient number, since it is larger than the sum of its proper divisors (19593).

91230991 is a wasteful number, since it uses less digits than its factorization.

91230991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19592.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 91230991 is about 9551.4915589137. The cubic root of 91230991 is about 450.1744031810.

The spelling of 91230991 in words is "ninety-one million, two hundred thirty thousand, nine hundred ninety-one".