91543619581 has 4 divisors (see below), whose sum is σ = 91552967712. Its totient is φ = 91534271452.

The previous prime is 91543619567. The next prime is 91543619599. The reversal of 91543619581 is 18591634519.

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-91543619581 is a prime.

It is a super-2 number, since 2×91543619581² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91543619501) 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, 4659361 + ... + 4678966.

It is an arithmetic number, because the mean of its divisors is an integer number (22888241928).

Almost surely, 2^91543619581 is an apocalyptic number.

It is an amenable number.

91543619581 is a deficient number, since it is larger than the sum of its proper divisors (9348131).

91543619581 is an equidigital number, since it uses as much as digits as its factorization.

91543619581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9348130.

The product of its digits is 1166400, while the sum is 52.

The spelling of 91543619581 in words is "ninety-one billion, five hundred forty-three million, six hundred nineteen thousand, five hundred eighty-one".