12138521 has 2 divisors, whose sum is σ = 12138522. Its totient is φ = 12138520.

The previous prime is 12138499. The next prime is 12138523. The reversal of 12138521 is 12583121.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11978521 + 160000 = 3461^2 + 400^2 .

It is an emirp because it is prime and its reverse (12583121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 12138521 - 2¹⁰ = 12137497 is a prime.

Together with 12138523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (12138523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6069260 + 6069261.

It is an arithmetic number, because the mean of its divisors is an integer number (6069261).

Almost surely, 2^12138521 is an apocalyptic number.

It is an amenable number.

12138521 is a deficient number, since it is larger than the sum of its proper divisors (1).

12138521 is an equidigital number, since it uses as much as digits as its factorization.

12138521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 480, while the sum is 23.

The square root of 12138521 is about 3484.0380307913. The cubic root of 12138521 is about 229.8204080090.

The spelling of 12138521 in words is "twelve million, one hundred thirty-eight thousand, five hundred twenty-one".