81118638 has 32 divisors (see below), whose sum is σ = 189753600. Its totient is φ = 25616088.

The previous prime is 81118637. The next prime is 81118643. The reversal of 81118638 is 83681118.

81118638 is a `hidden beast` number, since 8 + 1 + 1 + 18 + 638 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81118633) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38506 + ... + 40557.

It is an arithmetic number, because the mean of its divisors is an integer number (5929800).

Almost surely, 2^81118638 is an apocalyptic number.

81118638 is an abundant number, since it is smaller than the sum of its proper divisors (108634962).

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

81118638 is a wasteful number, since it uses less digits than its factorization.

81118638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79093 (or 79087 counting only the distinct ones).

The product of its digits is 9216, while the sum is 36.

The square root of 81118638 is about 9006.5885883613. The cubic root of 81118638 is about 432.8860095303.

The spelling of 81118638 in words is "eighty-one million, one hundred eighteen thousand, six hundred thirty-eight".