18188161 has 4 divisors (see below), whose sum is σ = 18201924. Its totient is φ = 18174400.

The previous prime is 18188123. The next prime is 18188167. The reversal of 18188161 is 16188181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12215025 + 5973136 = 3495^2 + 2444^2 .

It is a cyclic number.

It is not a de Polignac number, because 18188161 - 2⁷ = 18188033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18188167) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4660 + ... + 7621.

It is an arithmetic number, because the mean of its divisors is an integer number (4550481).

Almost surely, 2^18188161 is an apocalyptic number.

It is an amenable number.

18188161 is a deficient number, since it is larger than the sum of its proper divisors (13763).

18188161 is a wasteful number, since it uses less digits than its factorization.

18188161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13762.

The product of its digits is 3072, while the sum is 34.

The square root of 18188161 is about 4264.7580236163. The cubic root of 18188161 is about 262.9841634361.

The spelling of 18188161 in words is "eighteen million, one hundred eighty-eight thousand, one hundred sixty-one".