81615568896 has 300 divisors, whose sum is σ = 246928179960. Its totient is φ = 26860584960.

The previous prime is 81615568847. The next prime is 81615568901. The reversal of 81615568896 is 69886551618.

81615568896 is a `hidden beast` number, since 8 + 1 + 61 + 5 + 568 + 8 + 9 + 6 = 666.

It is a super-2 number, since 2×81615568896² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 118111911 + ... + 118112601.

Almost surely, 2^81615568896 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 81615568896, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123464089980).

81615568896 is an abundant number, since it is smaller than the sum of its proper divisors (165312611064).

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

81615568896 is an frugal number, since it uses more digits than its factorization.

81615568896 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 820 (or 785 counting only the distinct ones).

The product of its digits is 24883200, while the sum is 63.

The spelling of 81615568896 in words is "eighty-one billion, six hundred fifteen million, five hundred sixty-eight thousand, eight hundred ninety-six".