81855818 has 16 divisors (see below), whose sum is σ = 135005184. Its totient is φ = 36912960.

The previous prime is 81855817. The next prime is 81855859.

81855818 is nontrivially palindromic in base 10.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81855817) 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, 11855 + ... + 17442.

It is an arithmetic number, because the mean of its divisors is an integer number (8437824).

Almost surely, 2^81855818 is an apocalyptic number.

81855818 is a deficient number, since it is larger than the sum of its proper divisors (53149366).

81855818 is a wasteful number, since it uses less digits than its factorization.

81855818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29437.

The product of its digits is 102400, while the sum is 44.

The square root of 81855818 is about 9047.4205163682. The cubic root of 81855818 is about 434.1933666570.

The spelling of 81855818 in words is "eighty-one million, eight hundred fifty-five thousand, eight hundred eighteen".