81136326768 has 160 divisors (see below), whose sum is σ = 256149319680. Its totient is φ = 21601996800.

The previous prime is 81136326767. The next prime is 81136326773. The reversal of 81136326768 is 86762363118.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 81136326768.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81136326767) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 506593 + ... + 647231.

It is an arithmetic number, because the mean of its divisors is an integer number (1600933248).

Almost surely, 2^81136326768 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 81136326768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (128074659840).

81136326768 is an abundant number, since it is smaller than the sum of its proper divisors (175012992912).

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

81136326768 is a wasteful number, since it uses less digits than its factorization.

81136326768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140775 (or 140769 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 51.

The spelling of 81136326768 in words is "eighty-one billion, one hundred thirty-six million, three hundred twenty-six thousand, seven hundred sixty-eight".