81368881856 has 112 divisors (see below), whose sum is σ = 171820758720. Its totient is φ = 38149816320.

The previous prime is 81368881849. The next prime is 81368881883. The reversal of 81368881856 is 65818886318.

It is a Smith number, since the sum of its digits (62) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 30258560 + ... + 30261248.

Almost surely, 2^81368881856 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 81368881856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (85910379360).

81368881856 is an abundant number, since it is smaller than the sum of its proper divisors (90451876864).

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

81368881856 is a wasteful number, since it uses less digits than its factorization.

81368881856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3122 (or 3112 counting only the distinct ones).

The product of its digits is 17694720, while the sum is 62.

The spelling of 81368881856 in words is "eighty-one billion, three hundred sixty-eight million, eight hundred eighty-one thousand, eight hundred fifty-six".