81856118 has 4 divisors (see below), whose sum is σ = 122784180. Its totient is φ = 40928058.

The previous prime is 81856109. The next prime is 81856147. The reversal of 81856118 is 81165818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81165818 = 2 ⋅40582909.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20464028 + ... + 20464031.

It is an arithmetic number, because the mean of its divisors is an integer number (30696045).

Almost surely, 2^81856118 is an apocalyptic number.

81856118 is a deficient number, since it is larger than the sum of its proper divisors (40928062).

81856118 is a wasteful number, since it uses less digits than its factorization.

81856118 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40928061.

The product of its digits is 15360, while the sum is 38.

The square root of 81856118 is about 9047.4370956642. The cubic root of 81856118 is about 434.1938970931.

The spelling of 81856118 in words is "eighty-one million, eight hundred fifty-six thousand, one hundred eighteen".