18009681 has 16 divisors (see below), whose sum is σ = 25579008. Its totient is φ = 11232000.

The previous prime is 18009679. The next prime is 18009683. The reversal of 18009681 is 18690081.

It is an interprime number because it is at equal distance from previous prime (18009679) and next prime (18009683).

It is not a de Polignac number, because 18009681 - 2¹ = 18009679 is a prime.

It is a super-2 number, since 2×18009681² = 648697219443522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18009683) 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, 8256 + ... + 10206.

It is an arithmetic number, because the mean of its divisors is an integer number (1598688).

Almost surely, 2^18009681 is an apocalyptic number.

It is an amenable number.

18009681 is a deficient number, since it is larger than the sum of its proper divisors (7569327).

18009681 is a wasteful number, since it uses less digits than its factorization.

18009681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2152.

The product of its (nonzero) digits is 3456, while the sum is 33.

The square root of 18009681 is about 4243.7814505462. The cubic root of 18009681 is about 262.1211150695.

The spelling of 18009681 in words is "eighteen million, nine thousand, six hundred eighty-one".