81941172768 has 432 divisors, whose sum is σ = 293044129560. Its totient is φ = 21527396352.

The previous prime is 81941172763. The next prime is 81941172773. The reversal of 81941172768 is 86727114918.

It is an interprime number because it is at equal distance from previous prime (81941172763) and next prime (81941172773).

It can be written as a sum of positive squares in 4 ways, for example, as 10901865744 + 71039307024 = 104412^2 + 266532^2 .

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

It is not an unprimeable number, because it can be changed into a prime (81941172763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 58154848 + ... + 58156256.

Almost surely, 2^81941172768 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 81941172768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146522064780).

81941172768 is an abundant number, since it is smaller than the sum of its proper divisors (211102956792).

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

81941172768 is a wasteful number, since it uses less digits than its factorization.

81941172768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1769 (or 1751 counting only the distinct ones).

The product of its digits is 1354752, while the sum is 54.

The spelling of 81941172768 in words is "eighty-one billion, nine hundred forty-one million, one hundred seventy-two thousand, seven hundred sixty-eight".