81537361728 has 112 divisors (see below), whose sum is σ = 217429445760. Its totient is φ = 26966016000.

The previous prime is 81537361693. The next prime is 81537361733. The reversal of 81537361728 is 82716373518.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38297368 + ... + 38299496.

Almost surely, 2^81537361728 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 81537361728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108714722880).

81537361728 is an abundant number, since it is smaller than the sum of its proper divisors (135892084032).

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

81537361728 is a wasteful number, since it uses less digits than its factorization.

81537361728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3616 (or 3606 counting only the distinct ones).

The product of its digits is 1693440, while the sum is 51.

The spelling of 81537361728 in words is "eighty-one billion, five hundred thirty-seven million, three hundred sixty-one thousand, seven hundred twenty-eight".