81811928016 has 480 divisors, whose sum is σ = 295787318400. Its totient is φ = 21459271680.

The previous prime is 81811927991. The next prime is 81811928017. The reversal of 81811928016 is 61082911818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81811928017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 58063120 + ... + 58064528.

It is an arithmetic number, because the mean of its divisors is an integer number (616223580).

Almost surely, 2^81811928016 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81811928016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147893659200).

81811928016 is an abundant number, since it is smaller than the sum of its proper divisors (213975390384).

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

81811928016 is a wasteful number, since it uses less digits than its factorization.

81811928016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1664 (or 1645 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 45.

The spelling of 81811928016 in words is "eighty-one billion, eight hundred eleven million, nine hundred twenty-eight thousand, sixteen".