91581817 has 4 divisors (see below), whose sum is σ = 91624960. Its totient is φ = 91538676.

The previous prime is 91581779. The next prime is 91581821. The reversal of 91581817 is 71818519.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-91581817 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 91581817.

It is not an unprimeable number, because it can be changed into a prime (91581877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18213 + ... + 22690.

It is an arithmetic number, because the mean of its divisors is an integer number (22906240).

Almost surely, 2^91581817 is an apocalyptic number.

It is an amenable number.

91581817 is a deficient number, since it is larger than the sum of its proper divisors (43143).

91581817 is a wasteful number, since it uses less digits than its factorization.

91581817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43142.

The product of its digits is 20160, while the sum is 40.

The square root of 91581817 is about 9569.8389223644. The cubic root of 91581817 is about 450.7507090788.

The spelling of 91581817 in words is "ninety-one million, five hundred eighty-one thousand, eight hundred seventeen".