81311705824 has 24 divisors (see below), whose sum is σ = 162706726728. Its totient is φ = 39989362560.

The previous prime is 81311705819. The next prime is 81311705851. The reversal of 81311705824 is 42850711318.

It is a super-2 number, since 2×81311705824² (a number of 23 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 3 ways as a sum of consecutive naturals, for example, 20825842 + ... + 20829745.

It is an arithmetic number, because the mean of its divisors is an integer number (6779446947).

Almost surely, 2^81311705824 is an apocalyptic number.

It is an amenable number.

81311705824 is an abundant number, since it is smaller than the sum of its proper divisors (81395020904).

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

81311705824 is a wasteful number, since it uses less digits than its factorization.

81311705824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41655658 (or 41655650 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 40.

The spelling of 81311705824 in words is "eighty-one billion, three hundred eleven million, seven hundred five thousand, eight hundred twenty-four".