18185861 has 4 divisors (see below), whose sum is σ = 18608832. Its totient is φ = 17762892.

The previous prime is 18185821. The next prime is 18185891. The reversal of 18185861 is 16858181.

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: 16858181 = 2081 ⋅8101.

It is a cyclic number.

It is not a de Polignac number, because 18185861 - 2¹⁴ = 18169477 is a prime.

It is a super-2 number, since 2×18185861² = 661451080622642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18185821) 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 3 ways as a sum of consecutive naturals, for example, 211421 + ... + 211506.

It is an arithmetic number, because the mean of its divisors is an integer number (4652208).

Almost surely, 2^18185861 is an apocalyptic number.

It is an amenable number.

18185861 is a deficient number, since it is larger than the sum of its proper divisors (422971).

18185861 is an equidigital number, since it uses as much as digits as its factorization.

18185861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 422970.

The product of its digits is 15360, while the sum is 38.

The square root of 18185861 is about 4264.4883632155. The cubic root of 18185861 is about 262.9730776704.

The spelling of 18185861 in words is "eighteen million, one hundred eighty-five thousand, eight hundred sixty-one".