81109776384 has 768 divisors, whose sum is σ = 300867840000. Its totient is φ = 21284093952.

The previous prime is 81109776383. The next prime is 81109776409. The reversal of 81109776384 is 48367790118.

It is a tau number, because it is divible by the number of its divisors (768).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 81109776384.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81109776383) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 407586717 + ... + 407586915.

It is an arithmetic number, because the mean of its divisors is an integer number (391755000).

Almost surely, 2^81109776384 is an apocalyptic number.

81109776384 is a gapful number since it is divisible by the number (84) 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 81109776384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150433920000).

81109776384 is an abundant number, since it is smaller than the sum of its proper divisors (219758063616).

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

81109776384 is an equidigital number, since it uses as much as digits as its factorization.

81109776384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262 (or 224 counting only the distinct ones).

The product of its (nonzero) digits is 2032128, while the sum is 54.

The spelling of 81109776384 in words is "eighty-one billion, one hundred nine million, seven hundred seventy-six thousand, three hundred eighty-four".