81865728000 has 1344 divisors, whose sum is σ = 357232232448. Its totient is φ = 18314035200.

The previous prime is 81865727959. The next prime is 81865728011. The reversal of 81865728000 is 82756818.

It is a tau number, because it is divible by the number of its divisors (1344).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1741823977 + ... + 1741824023.

It is an arithmetic number, because the mean of its divisors is an integer number (265797792).

Almost surely, 2^81865728000 is an apocalyptic number.

81865728000 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81865728000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (178616116224).

81865728000 is an abundant number, since it is smaller than the sum of its proper divisors (275366504448).

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

81865728000 is an frugal number, since it uses more digits than its factorization.

81865728000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110 (or 64 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 45.

The spelling of 81865728000 in words is "eighty-one billion, eight hundred sixty-five million, seven hundred twenty-eight thousand".