81109057536 has 576 divisors, whose sum is σ = 271286547840. Its totient is φ = 23781703680.

The previous prime is 81109057487. The next prime is 81109057591. The reversal of 81109057536 is 63575090118.

It is a happy number.

81109057536 is a `hidden beast` number, since 8 + 1 + 109 + 0 + 5 + 7 + 536 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

It is a junction number, because it is equal to n+sod(n) for n = 81109057491 and 81109057500.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1886257131 + ... + 1886257173.

It is an arithmetic number, because the mean of its divisors is an integer number (470983590).

Almost surely, 2^81109057536 is an apocalyptic number.

81109057536 is a gapful number since it is divisible by the number (86) 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 81109057536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135643273920).

81109057536 is an abundant number, since it is smaller than the sum of its proper divisors (190177490304).

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

81109057536 is an equidigital number, since it uses as much as digits as its factorization.

81109057536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140 (or 102 counting only the distinct ones).

The product of its (nonzero) digits is 226800, while the sum is 45.

The spelling of 81109057536 in words is "eighty-one billion, one hundred nine million, fifty-seven thousand, five hundred thirty-six".