18166861 has 2 divisors, whose sum is σ = 18166862. Its totient is φ = 18166860.

The previous prime is 18166843. The next prime is 18166871. The reversal of 18166861 is 16866181.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10432900 + 7733961 = 3230^2 + 2781^2 .

It is a cyclic number.

It is not a de Polignac number, because 18166861 - 2¹¹ = 18164813 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18166861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18166801) 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, 9083430 + 9083431.

It is an arithmetic number, because the mean of its divisors is an integer number (9083431).

Almost surely, 2^18166861 is an apocalyptic number.

It is an amenable number.

18166861 is a deficient number, since it is larger than the sum of its proper divisors (1).

18166861 is an equidigital number, since it uses as much as digits as its factorization.

18166861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13824, while the sum is 37.

The square root of 18166861 is about 4262.2600812245. The cubic root of 18166861 is about 262.8814638329.

The spelling of 18166861 in words is "eighteen million, one hundred sixty-six thousand, eight hundred sixty-one".