12917221 has 2 divisors, whose sum is σ = 12917222. Its totient is φ = 12917220.

The previous prime is 12917183. The next prime is 12917239. The reversal of 12917221 is 12271921.

12917221 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., 12602500 + 314721 = 3550^2 + 561^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12917221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12917291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6458610 + 6458611.

It is an arithmetic number, because the mean of its divisors is an integer number (6458611).

Almost surely, 2^12917221 is an apocalyptic number.

It is an amenable number.

12917221 is a deficient number, since it is larger than the sum of its proper divisors (1).

12917221 is an equidigital number, since it uses as much as digits as its factorization.

12917221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 504, while the sum is 25.

The square root of 12917221 is about 3594.0535610923. The cubic root of 12917221 is about 234.6333258615.

The spelling of 12917221 in words is "twelve million, nine hundred seventeen thousand, two hundred twenty-one".