18211181 has 2 divisors, whose sum is σ = 18211182. Its totient is φ = 18211180.

The previous prime is 18211163. The next prime is 18211189. The reversal of 18211181 is 18111281.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17355556 + 855625 = 4166^2 + 925^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18211181 is a prime.

It is a super-2 number, since 2×18211181² = 663294226829522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18211189) 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 as a sum of consecutive naturals, namely, 9105590 + 9105591.

It is an arithmetic number, because the mean of its divisors is an integer number (9105591).

Almost surely, 2^18211181 is an apocalyptic number.

It is an amenable number.

18211181 is a deficient number, since it is larger than the sum of its proper divisors (1).

18211181 is an equidigital number, since it uses as much as digits as its factorization.

18211181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 128, while the sum is 23.

The square root of 18211181 is about 4267.4560337513. The cubic root of 18211181 is about 263.0950660388.

The spelling of 18211181 in words is "eighteen million, two hundred eleven thousand, one hundred eighty-one".