81138112 has 56 divisors (see below), whose sum is σ = 183318912. Its totient is φ = 35270400.

The previous prime is 81138107. The next prime is 81138131. The reversal of 81138112 is 21183118.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13687 + ... + 18697.

It is an arithmetic number, because the mean of its divisors is an integer number (3273552).

Almost surely, 2^81138112 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 81138112, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (91659456).

81138112 is an abundant number, since it is smaller than the sum of its proper divisors (102180800).

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

81138112 is a wasteful number, since it uses less digits than its factorization.

81138112 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5057 (or 5047 counting only the distinct ones).

The product of its digits is 384, while the sum is 25.

The square root of 81138112 is about 9007.6696209397. The cubic root of 81138112 is about 432.9206474707.

The spelling of 81138112 in words is "eighty-one million, one hundred thirty-eight thousand, one hundred twelve".