18305681 has 4 divisors (see below), whose sum is σ = 18378864. Its totient is φ = 18232500.

The previous prime is 18305669. The next prime is 18305711. The reversal of 18305681 is 18650381.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18650381 = 19 ⋅981599.

It is a cyclic number.

It is not a de Polignac number, because 18305681 - 2¹⁸ = 18043537 is a prime.

It is a super-2 number, since 2×18305681² = 670195913747522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18305611) 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 3 ways as a sum of consecutive naturals, for example, 36215 + ... + 36716.

It is an arithmetic number, because the mean of its divisors is an integer number (4594716).

Almost surely, 2^18305681 is an apocalyptic number.

It is an amenable number.

18305681 is a deficient number, since it is larger than the sum of its proper divisors (73183).

18305681 is an equidigital number, since it uses as much as digits as its factorization.

18305681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73182.

The product of its (nonzero) digits is 5760, while the sum is 32.

The square root of 18305681 is about 4278.5138775047. The cubic root of 18305681 is about 263.5493584226.

The spelling of 18305681 in words is "eighteen million, three hundred five thousand, six hundred eighty-one".