81120018 has 32 divisors (see below), whose sum is σ = 191813760. Its totient is φ = 22377600.

The previous prime is 81120007. The next prime is 81120071. The reversal of 81120018 is 81002118.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 81119976 and 81120003.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32083 + ... + 34518.

It is an arithmetic number, because the mean of its divisors is an integer number (5994180).

Almost surely, 2^81120018 is an apocalyptic number.

81120018 is an abundant number, since it is smaller than the sum of its proper divisors (110693742).

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

81120018 is a wasteful number, since it uses less digits than its factorization.

81120018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66642.

The product of its (nonzero) digits is 128, while the sum is 21.

The square root of 81120018 is about 9006.6651986182. The cubic root of 81120018 is about 432.8884642860. Note that the first 3 decimals are identical.

The spelling of 81120018 in words is "eighty-one million, one hundred twenty thousand, eighteen".