81845996617728 has 1296 divisors, whose sum is σ = 297115141115520. Its totient is φ = 21994423713792.

The previous prime is 81845996617703. The next prime is 81845996617739. The reversal of 81845996617728 is 82771669954818.

81845996617728 is a `hidden beast` number, since 8 + 1 + 8 + 4 + 599 + 6 + 6 + 17 + 7 + 2 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (1296).

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 588820119483 + ... + 588820119621.

It is an arithmetic number, because the mean of its divisors is an integer number (229255510120).

Almost surely, 2^{81845996617728} 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 81845996617728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148557570557760).

81845996617728 is an abundant number, since it is smaller than the sum of its proper divisors (215269144497792).

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

81845996617728 is an frugal number, since it uses more digits than its factorization.

81845996617728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353 (or 170 counting only the distinct ones).

The product of its digits is 2926264320, while the sum is 81.

The spelling of 81845996617728 in words is "eighty-one trillion, eight hundred forty-five billion, nine hundred ninety-six million, six hundred seventeen thousand, seven hundred twenty-eight".