81931161288704 has 1440 divisors, whose sum is σ = 225919290240000. Its totient is φ = 29345433255936.

The previous prime is 81931161288643. The next prime is 81931161288709. The reversal of 81931161288704 is 40788216113918.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (59).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81931161288709) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 549873565622 + ... + 549873565770.

It is an arithmetic number, because the mean of its divisors is an integer number (156888396000).

Almost surely, 2^{81931161288704} 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 81931161288704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112959645120000).

81931161288704 is an abundant number, since it is smaller than the sum of its proper divisors (143988128951296).

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

81931161288704 is a wasteful number, since it uses less digits than its factorization.

81931161288704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 329 (or 296 counting only the distinct ones).

The product of its (nonzero) digits is 4644864, while the sum is 59.

The spelling of 81931161288704 in words is "eighty-one trillion, nine hundred thirty-one billion, one hundred sixty-one million, two hundred eighty-eight thousand, seven hundred four".