81081738 has 48 divisors (see below), whose sum is σ = 192446280. Its totient is φ = 24557568.

The previous prime is 81081731. The next prime is 81081769. The reversal of 81081738 is 83718018.

It can be written as a sum of positive squares in 4 ways, for example, as 57198969 + 23882769 = 7563^2 + 4887^2 .

It is not an unprimeable number, because it can be changed into a prime (81081731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4306 + ... + 13442.

Almost surely, 2^81081738 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81081738, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96223140).

81081738 is an abundant number, since it is smaller than the sum of its proper divisors (111364542).

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

81081738 is a wasteful number, since it uses less digits than its factorization.

81081738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9191 (or 9188 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 81081738 is about 9004.5398549843. The cubic root of 81081738 is about 432.8203611713.

The spelling of 81081738 in words is "eighty-one million, eighty-one thousand, seven hundred thirty-eight".