81237984728 has 64 divisors (see below), whose sum is σ = 164803921920. Its totient is φ = 37402892800.

The previous prime is 81237984719. The next prime is 81237984731. The reversal of 81237984728 is 82748973218.

It is a super-2 number, since 2×81237984728² (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 15 ways as a sum of consecutive naturals, for example, 1232825 + ... + 1297047.

It is an arithmetic number, because the mean of its divisors is an integer number (2575061280).

Almost surely, 2^81237984728 is an apocalyptic number.

It is an amenable number.

81237984728 is an abundant number, since it is smaller than the sum of its proper divisors (83565937192).

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

81237984728 is a wasteful number, since it uses less digits than its factorization.

81237984728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64448 (or 64444 counting only the distinct ones).

The product of its digits is 10838016, while the sum is 59.

The spelling of 81237984728 in words is "eighty-one billion, two hundred thirty-seven million, nine hundred eighty-four thousand, seven hundred twenty-eight".