81704891136 has 144 divisors (see below), whose sum is σ = 237669844608. Its totient is φ = 24712396800.

The previous prime is 81704891069. The next prime is 81704891141. The reversal of 81704891136 is 63119840718.

It is a super-2 number, since 2×81704891136² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4612216 + ... + 4629896.

It is an arithmetic number, because the mean of its divisors is an integer number (1650485032).

Almost surely, 2^81704891136 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 81704891136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118834922304).

81704891136 is an abundant number, since it is smaller than the sum of its proper divisors (155964953472).

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

81704891136 is a wasteful number, since it uses less digits than its factorization.

81704891136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18258 (or 18244 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 48.

The spelling of 81704891136 in words is "eighty-one billion, seven hundred four million, eight hundred ninety-one thousand, one hundred thirty-six".