81091594784816 has 240 divisors, whose sum is σ = 201608636221440. Its totient is φ = 30915505420800.

The previous prime is 81091594784797. The next prime is 81091594784821. The reversal of 81091594784816 is 61848749519018.

It is a self number, because there is not a number n which added to its sum of digits gives 81091594784816.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4050316886 + ... + 4050336906.

It is an arithmetic number, because the mean of its divisors is an integer number (840035984256).

Almost surely, 2^{81091594784816} 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 81091594784816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (100804318110720).

81091594784816 is an abundant number, since it is smaller than the sum of its proper divisors (120517041436624).

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

81091594784816 is a wasteful number, since it uses less digits than its factorization.

81091594784816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26464 (or 26447 counting only the distinct ones).

The product of its (nonzero) digits is 139345920, while the sum is 71.

The spelling of 81091594784816 in words is "eighty-one trillion, ninety-one billion, five hundred ninety-four million, seven hundred eighty-four thousand, eight hundred sixteen".