18191161 has 4 divisors (see below), whose sum is σ = 18682852. Its totient is φ = 17699472.

The previous prime is 18191153. The next prime is 18191171. The reversal of 18191161 is 16119181.

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 6760000 + 11431161 = 2600^2 + 3381^2 .

It is a cyclic number.

It is not a de Polignac number, because 18191161 - 2³ = 18191153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18191101) 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, 245790 + ... + 245863.

It is an arithmetic number, because the mean of its divisors is an integer number (4670713).

Almost surely, 2^18191161 is an apocalyptic number.

It is an amenable number.

18191161 is a deficient number, since it is larger than the sum of its proper divisors (491691).

18191161 is an equidigital number, since it uses as much as digits as its factorization.

18191161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 491690.

The product of its digits is 432, while the sum is 28.

The square root of 18191161 is about 4265.1097289519. The cubic root of 18191161 is about 262.9986217260.

The spelling of 18191161 in words is "eighteen million, one hundred ninety-one thousand, one hundred sixty-one".