18168561 has 6 divisors (see below), whose sum is σ = 26243490. Its totient is φ = 12112368.

The previous prime is 18168539. The next prime is 18168569. The reversal of 18168561 is 16586181.

It can be written as a sum of positive squares in only one way, i.e., 9960336 + 8208225 = 3156^2 + 2865^2 .

It is not a de Polignac number, because 18168561 - 2⁷ = 18168433 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18168569) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 1009356 + ... + 1009373.

It is an arithmetic number, because the mean of its divisors is an integer number (4373915).

Almost surely, 2^18168561 is an apocalyptic number.

It is an amenable number.

18168561 is a deficient number, since it is larger than the sum of its proper divisors (8074929).

18168561 is a wasteful number, since it uses less digits than its factorization.

18168561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2018735 (or 2018732 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 18168561 is about 4262.4595012739. The cubic root of 18168561 is about 262.8896634617.

The spelling of 18168561 in words is "eighteen million, one hundred sixty-eight thousand, five hundred sixty-one".