81312872664816 has 240 divisors, whose sum is σ = 250504166290560. Its totient is φ = 24465299927040.

The previous prime is 81312872664797. The next prime is 81312872664847. The reversal of 81312872664816 is 61846627821318.

81312872664816 is a `hidden beast` number, since 8 + 1 + 3 + 1 + 28 + 72 + 66 + 481 + 6 = 666.

It is a super-2 number, since 2×81312872664816² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 98924646 + ... + 99743226.

It is an arithmetic number, because the mean of its divisors is an integer number (1043767359544).

Almost surely, 2^{81312872664816} 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 81312872664816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125252083145280).

81312872664816 is an abundant number, since it is smaller than the sum of its proper divisors (169191293625744).

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

81312872664816 is a wasteful number, since it uses less digits than its factorization.

81312872664816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 819784 (or 819775 counting only the distinct ones).

The product of its digits is 37158912, while the sum is 63.

The spelling of 81312872664816 in words is "eighty-one trillion, three hundred twelve billion, eight hundred seventy-two million, six hundred sixty-four thousand, eight hundred sixteen".