81565704000 has 560 divisors, whose sum is σ = 329209822656. Its totient is φ = 19771776000.

The previous prime is 81565703951. The next prime is 81565704037. The reversal of 81565704000 is 40756518.

81565704000 is a `hidden beast` number, since 81 + 5 + 6 + 570 + 4 + 0 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 7122279 + ... + 7133721.

Almost surely, 2^81565704000 is an apocalyptic number.

81565704000 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 81565704000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (164604911328).

81565704000 is an abundant number, since it is smaller than the sum of its proper divisors (247644118656).

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

81565704000 is a wasteful number, since it uses less digits than its factorization.

81565704000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11493 (or 11464 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 36.

The spelling of 81565704000 in words is "eighty-one billion, five hundred sixty-five million, seven hundred four thousand".