81171564 has 24 divisors (see below), whose sum is σ = 189547008. Its totient is φ = 27036240.

The previous prime is 81171529. The next prime is 81171581. The reversal of 81171564 is 46517118.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26269 + ... + 29195.

It is an arithmetic number, because the mean of its divisors is an integer number (7897792).

Almost surely, 2^81171564 is an apocalyptic number.

It is an amenable number.

81171564 is an abundant number, since it is smaller than the sum of its proper divisors (108375444).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81171564 is a wasteful number, since it uses less digits than its factorization.

81171564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5245 (or 5243 counting only the distinct ones).

The product of its digits is 6720, while the sum is 33.

The square root of 81171564 is about 9009.5262916537. The cubic root of 81171564 is about 432.9801348122.

The spelling of 81171564 in words is "eighty-one million, one hundred seventy-one thousand, five hundred sixty-four".