18015681 has 16 divisors (see below), whose sum is σ = 24915968. Its totient is φ = 11566800.

The previous prime is 18015677. The next prime is 18015689. The reversal of 18015681 is 18651081.

It is a happy number.

It is not a de Polignac number, because 18015681 - 2² = 18015677 is a prime.

It is a super-2 number, since 2×18015681² = 649129523787522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18015689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28236 + ... + 28866.

It is an arithmetic number, because the mean of its divisors is an integer number (1557248).

Almost surely, 2^18015681 is an apocalyptic number.

It is an amenable number.

18015681 is a deficient number, since it is larger than the sum of its proper divisors (6900287).

18015681 is a wasteful number, since it uses less digits than its factorization.

18015681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 972.

The product of its (nonzero) digits is 1920, while the sum is 30.

The square root of 18015681 is about 4244.4883083830. The cubic root of 18015681 is about 262.1502207501.

The spelling of 18015681 in words is "eighteen million, fifteen thousand, six hundred eighty-one".