81811923589 has 8 divisors (see below), whose sum is σ = 89307007200. Its totient is φ = 74326446000.

The previous prime is 81811923563. The next prime is 81811923593. The reversal of 81811923589 is 98532911818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81811923589 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 (81811926589) 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 7 ways as a sum of consecutive naturals, for example, 2383687 + ... + 2417764.

It is an arithmetic number, because the mean of its divisors is an integer number (11163375900).

Almost surely, 2^81811923589 is an apocalyptic number.

It is an amenable number.

81811923589 is a deficient number, since it is larger than the sum of its proper divisors (7495083611).

81811923589 is a wasteful number, since it uses less digits than its factorization.

81811923589 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4803011.

The product of its digits is 1244160, while the sum is 55.

The spelling of 81811923589 in words is "eighty-one billion, eight hundred eleven million, nine hundred twenty-three thousand, five hundred eighty-nine".