12138821 has 2 divisors, whose sum is σ = 12138822. Its totient is φ = 12138820.

The previous prime is 12138811. The next prime is 12138827. The reversal of 12138821 is 12883121.

12138821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10329796 + 1809025 = 3214^2 + 1345^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12138821 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12138827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6069410 + 6069411.

It is an arithmetic number, because the mean of its divisors is an integer number (6069411).

Almost surely, 2^12138821 is an apocalyptic number.

It is an amenable number.

12138821 is a deficient number, since it is larger than the sum of its proper divisors (1).

12138821 is an equidigital number, since it uses as much as digits as its factorization.

12138821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 26.

The square root of 12138821 is about 3484.0810840163. The cubic root of 12138821 is about 229.8223013081.

The spelling of 12138821 in words is "twelve million, one hundred thirty-eight thousand, eight hundred twenty-one".