18164561 has 2 divisors, whose sum is σ = 18164562. Its totient is φ = 18164560.

The previous prime is 18164539. The next prime is 18164579. The reversal of 18164561 is 16546181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18105025 + 59536 = 4255^2 + 244^2 .

It is an emirp because it is prime and its reverse (16546181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18164561 - 2¹⁴ = 18148177 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18164161) 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 as a sum of consecutive naturals, namely, 9082280 + 9082281.

It is an arithmetic number, because the mean of its divisors is an integer number (9082281).

Almost surely, 2^18164561 is an apocalyptic number.

It is an amenable number.

18164561 is a deficient number, since it is larger than the sum of its proper divisors (1).

18164561 is an equidigital number, since it uses as much as digits as its factorization.

18164561 is an odious number, because the sum of its binary digits is odd.

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

The square root of 18164561 is about 4261.9902627763. The cubic root of 18164561 is about 262.8703694032.

The spelling of 18164561 in words is "eighteen million, one hundred sixty-four thousand, five hundred sixty-one".