12456721 has 2 divisors, whose sum is σ = 12456722. Its totient is φ = 12456720.

The previous prime is 12456709. The next prime is 12456751. The reversal of 12456721 is 12765421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12327121 + 129600 = 3511^2 + 360^2 .

It is a cyclic number.

It is not a de Polignac number, because 12456721 - 2¹⁹ = 11932433 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 12456721.

It is not a weakly prime, because it can be changed into another prime (12456751) 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, 6228360 + 6228361.

It is an arithmetic number, because the mean of its divisors is an integer number (6228361).

Almost surely, 2^12456721 is an apocalyptic number.

It is an amenable number.

12456721 is a deficient number, since it is larger than the sum of its proper divisors (1).

12456721 is an equidigital number, since it uses as much as digits as its factorization.

12456721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3360, while the sum is 28.

The square root of 12456721 is about 3529.4080240176. The cubic root of 12456721 is about 231.8112875328.

The spelling of 12456721 in words is "twelve million, four hundred fifty-six thousand, seven hundred twenty-one".