81165431585 has 8 divisors (see below), whose sum is σ = 111312591936. Its totient is φ = 55656295920.

The previous prime is 81165431569. The next prime is 81165431617. The reversal of 81165431585 is 58513456118.

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

It is not a de Polignac number, because 81165431585 - 2⁴ = 81165431569 is a prime.

It is a super-2 number, since 2×81165431585² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1159506131 + ... + 1159506200.

It is an arithmetic number, because the mean of its divisors is an integer number (13914073992).

Almost surely, 2^81165431585 is an apocalyptic number.

It is an amenable number.

81165431585 is a deficient number, since it is larger than the sum of its proper divisors (30147160351).

81165431585 is a wasteful number, since it uses less digits than its factorization.

81165431585 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2319012343.

The product of its digits is 576000, while the sum is 47.

The spelling of 81165431585 in words is "eighty-one billion, one hundred sixty-five million, four hundred thirty-one thousand, five hundred eighty-five".