12815221 has 2 divisors, whose sum is σ = 12815222. Its totient is φ = 12815220.

The previous prime is 12815207. The next prime is 12815227. The reversal of 12815221 is 12251821.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12780625 + 34596 = 3575^2 + 186^2 .

It is a cyclic number.

It is not a de Polignac number, because 12815221 - 2⁹ = 12814709 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 12815192 and 12815201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12815227) 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, 6407610 + 6407611.

It is an arithmetic number, because the mean of its divisors is an integer number (6407611).

Almost surely, 2^12815221 is an apocalyptic number.

It is an amenable number.

12815221 is a deficient number, since it is larger than the sum of its proper divisors (1).

12815221 is an equidigital number, since it uses as much as digits as its factorization.

12815221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 320, while the sum is 22.

The square root of 12815221 is about 3579.8353314084. The cubic root of 12815221 is about 234.0141041490.

The spelling of 12815221 in words is "twelve million, eight hundred fifteen thousand, two hundred twenty-one".