81865734720 has 1008 divisors, whose sum is σ = 350300422080. Its totient is φ = 16094453760.

The previous prime is 81865734719. The next prime is 81865734809. The reversal of 81865734720 is 2743756818.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 108144582 + ... + 108145338.

It is an arithmetic number, because the mean of its divisors is an integer number (347520260).

Almost surely, 2^81865734720 is an apocalyptic number.

81865734720 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81865734720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (175150211040).

81865734720 is an abundant number, since it is smaller than the sum of its proper divisors (268434687360).

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

81865734720 is a wasteful number, since it uses less digits than its factorization.

81865734720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 832 (or 804 counting only the distinct ones).

The product of its (nonzero) digits is 2257920, while the sum is 51.

The spelling of 81865734720 in words is "eighty-one billion, eight hundred sixty-five million, seven hundred thirty-four thousand, seven hundred twenty".