81804397213440 has 864 divisors, whose sum is σ = 313321684515840. Its totient is φ = 19539084902400.

The previous prime is 81804397213423. The next prime is 81804397213481. The reversal of 81804397213440 is 4431279340818.

81804397213440 is a `hidden beast` number, since 8 + 1 + 8 + 0 + 439 + 72 + 134 + 4 + 0 = 666.

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, 26568493821 + ... + 26568496899.

It is an arithmetic number, because the mean of its divisors is an integer number (362640838560).

Almost surely, 2^{81804397213440} is an apocalyptic number.

81804397213440 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 81804397213440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (156660842257920).

81804397213440 is an abundant number, since it is smaller than the sum of its proper divisors (231517287302400).

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

81804397213440 is a wasteful number, since it uses less digits than its factorization.

81804397213440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6141 (or 6124 counting only the distinct ones).

The product of its (nonzero) digits is 4644864, while the sum is 54.

The spelling of 81804397213440 in words is "eighty-one trillion, eight hundred four billion, three hundred ninety-seven million, two hundred thirteen thousand, four hundred forty".