81599561262576 has 1080 divisors, whose sum is σ = 289453902990720. Its totient is φ = 22189574937600.

The previous prime is 81599561262539. The next prime is 81599561262631. The reversal of 81599561262576 is 67526216599518.

81599561262576 is a `hidden beast` number, since 8 + 1 + 5 + 9 + 9 + 561 + 2 + 6 + 2 + 57 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 215 ways as a sum of consecutive naturals, for example, 9726966990 + ... + 9726975378.

Almost surely, 2^{81599561262576} 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 81599561262576, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144726951495360).

81599561262576 is an abundant number, since it is smaller than the sum of its proper divisors (207854341728144).

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

81599561262576 is an equidigital number, since it uses as much as digits as its factorization.

81599561262576 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8527 (or 8493 counting only the distinct ones).

The product of its digits is 489888000, while the sum is 72.

The spelling of 81599561262576 in words is "eighty-one trillion, five hundred ninety-nine billion, five hundred sixty-one million, two hundred sixty-two thousand, five hundred seventy-six".