81715844728 has 32 divisors (see below), whose sum is σ = 179837964000. Its totient is φ = 34074559872.

The previous prime is 81715844719. The next prime is 81715844747. The reversal of 81715844728 is 82744851718.

It is a super-2 number, since 2×81715844728² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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, 19717003 + ... + 19721146.

It is an arithmetic number, because the mean of its divisors is an integer number (5619936375).

Almost surely, 2^81715844728 is an apocalyptic number.

It is an amenable number.

81715844728 is an abundant number, since it is smaller than the sum of its proper divisors (98122119272).

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

81715844728 is a wasteful number, since it uses less digits than its factorization.

81715844728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39438199 (or 39438195 counting only the distinct ones).

The product of its digits is 4014080, while the sum is 55.

The spelling of 81715844728 in words is "eighty-one billion, seven hundred fifteen million, eight hundred forty-four thousand, seven hundred twenty-eight".