12181861 has 2 divisors, whose sum is σ = 12181862. Its totient is φ = 12181860.

The previous prime is 12181859. The next prime is 12181867. The reversal of 12181861 is 16818121.

12181861 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9641025 + 2540836 = 3105^2 + 1594^2 .

It is an emirp because it is prime and its reverse (16818121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12181861 - 2¹ = 12181859 is a prime.

Together with 12181859, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12181867) 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, 6090930 + 6090931.

It is an arithmetic number, because the mean of its divisors is an integer number (6090931).

Almost surely, 2^12181861 is an apocalyptic number.

It is an amenable number.

12181861 is a deficient number, since it is larger than the sum of its proper divisors (1).

12181861 is an equidigital number, since it uses as much as digits as its factorization.

12181861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 768, while the sum is 28.

The square root of 12181861 is about 3490.2522831452. The cubic root of 12181861 is about 230.0936039924.

Adding to 12181861 its reverse (16818121), we get a palindrome (28999982).

The spelling of 12181861 in words is "twelve million, one hundred eighty-one thousand, eight hundred sixty-one".