81113440 has 48 divisors (see below), whose sum is σ = 193430160. Its totient is φ = 32140800.

The previous prime is 81113429. The next prime is 81113449. The reversal of 81113440 is 4431118.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81113449) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15115 + ... + 19765.

It is an arithmetic number, because the mean of its divisors is an integer number (4029795).

Almost surely, 2^81113440 is an apocalyptic number.

81113440 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 81113440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (96715080).

81113440 is an abundant number, since it is smaller than the sum of its proper divisors (112316720).

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

81113440 is a wasteful number, since it uses less digits than its factorization.

81113440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4775 (or 4767 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 81113440 is about 9006.3000172102. The cubic root of 81113440 is about 432.8767630341.

Adding to 81113440 its reverse (4431118), we get a palindrome (85544558).

The spelling of 81113440 in words is "eighty-one million, one hundred thirteen thousand, four hundred forty".