12186721 has 2 divisors, whose sum is σ = 12186722. Its totient is φ = 12186720.

The previous prime is 12186719. The next prime is 12186737. The reversal of 12186721 is 12768121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11826721 + 360000 = 3439^2 + 600^2 .

It is an emirp because it is prime and its reverse (12768121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12186721 - 2¹ = 12186719 is a prime.

Together with 12186719, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 12186721.

It is not a weakly prime, because it can be changed into another prime (12186781) 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, 6093360 + 6093361.

It is an arithmetic number, because the mean of its divisors is an integer number (6093361).

Almost surely, 2^12186721 is an apocalyptic number.

12186721 is the 2016-th hex number.

It is an amenable number.

12186721 is a deficient number, since it is larger than the sum of its proper divisors (1).

12186721 is an equidigital number, since it uses as much as digits as its factorization.

12186721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1344, while the sum is 28.

The square root of 12186721 is about 3490.9484384620. The cubic root of 12186721 is about 230.1241988317.

The spelling of 12186721 in words is "twelve million, one hundred eighty-six thousand, seven hundred twenty-one".