81385995768 has 256 divisors, whose sum is σ = 260272742400. Its totient is φ = 20591746560.

The previous prime is 81385995751. The next prime is 81385995791. The reversal of 81385995768 is 86759958318.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 34883530 + ... + 34885862.

It is an arithmetic number, because the mean of its divisors is an integer number (1016690400).

Almost surely, 2^81385995768 is an apocalyptic number.

81385995768 is a gapful number since it is divisible by the number (88) 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 81385995768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130136371200).

81385995768 is an abundant number, since it is smaller than the sum of its proper divisors (178886746632).

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

81385995768 is a wasteful number, since it uses less digits than its factorization.

81385995768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2842 (or 2838 counting only the distinct ones).

The product of its digits is 130636800, while the sum is 69.

The spelling of 81385995768 in words is "eighty-one billion, three hundred eighty-five million, nine hundred ninety-five thousand, seven hundred sixty-eight".