12656221 has 2 divisors, whose sum is σ = 12656222. Its totient is φ = 12656220.

The previous prime is 12656213. The next prime is 12656227. The reversal of 12656221 is 12265621.

12656221 is digitally balanced in base 2 and base 3, because in such bases 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., 12348196 + 308025 = 3514^2 + 555^2 .

It is a cyclic number.

It is not a de Polignac number, because 12656221 - 2³ = 12656213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12656227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6328110 + 6328111.

It is an arithmetic number, because the mean of its divisors is an integer number (6328111).

Almost surely, 2^12656221 is an apocalyptic number.

It is an amenable number.

12656221 is a deficient number, since it is larger than the sum of its proper divisors (1).

12656221 is an equidigital number, since it uses as much as digits as its factorization.

12656221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1440, while the sum is 25.

The square root of 12656221 is about 3557.5582918626. The cubic root of 12656221 is about 233.0422599519.

The spelling of 12656221 in words is "twelve million, six hundred fifty-six thousand, two hundred twenty-one".