18111681 has 40 divisors (see below), whose sum is σ = 32757120. Its totient is φ = 9735552.

The previous prime is 18111673. The next prime is 18111701. The reversal of 18111681 is 18611181.

18111681 is nontrivially palindromic in base 13.

It is not a de Polignac number, because 18111681 - 2³ = 18111673 is a prime.

It is a super-2 number, since 2×18111681² = 656065977291522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (18111601) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 8700 + ... + 10578.

It is an arithmetic number, because the mean of its divisors is an integer number (818928).

Almost surely, 2^18111681 is an apocalyptic number.

It is an amenable number.

18111681 is a deficient number, since it is larger than the sum of its proper divisors (14645439).

18111681 is a wasteful number, since it uses less digits than its factorization.

18111681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1915 (or 1906 counting only the distinct ones).

The product of its digits is 384, while the sum is 27.

The square root of 18111681 is about 4255.7820667887. The cubic root of 18111681 is about 262.6150352950.

Subtracting 18111681 from its reverse (18611181), we obtain a triangular number (499500 = T₉₉₉).

The spelling of 18111681 in words is "eighteen million, one hundred eleven thousand, six hundred eighty-one".