81506057472 has 324 divisors, whose sum is σ = 275832107460. Its totient is φ = 23077748736.

The previous prime is 81506057453. The next prime is 81506057483. The reversal of 81506057472 is 27475060518.

81506057472 is a `hidden beast` number, since 8 + 1 + 5 + 0 + 6 + 0 + 574 + 72 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 704583936 + 80801473536 = 26544^2 + 284256^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 12754054 + ... + 12760442.

It is an arithmetic number, because the mean of its divisors is an integer number (851333665).

Almost surely, 2^81506057472 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 81506057472, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137916053730).

81506057472 is an abundant number, since it is smaller than the sum of its proper divisors (194326049988).

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

81506057472 is a wasteful number, since it uses less digits than its factorization.

81506057472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6538 (or 6514 counting only the distinct ones).

The product of its (nonzero) digits is 470400, while the sum is 45.

The spelling of 81506057472 in words is "eighty-one billion, five hundred six million, fifty-seven thousand, four hundred seventy-two".