12646721 has 2 divisors, whose sum is σ = 12646722. Its totient is φ = 12646720.

The previous prime is 12646693. The next prime is 12646727. The reversal of 12646721 is 12764621.

12646721 is digitally balanced in base 3, 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., 6451600 + 6195121 = 2540^2 + 2489^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12646721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (12646727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6323360 + 6323361.

It is an arithmetic number, because the mean of its divisors is an integer number (6323361).

Almost surely, 2^12646721 is an apocalyptic number.

It is an amenable number.

12646721 is a deficient number, since it is larger than the sum of its proper divisors (1).

12646721 is an equidigital number, since it uses as much as digits as its factorization.

12646721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4032, while the sum is 29.

The square root of 12646721 is about 3556.2228557839. Note that the first 3 decimals coincide. The cubic root of 12646721 is about 232.9839367069.

The spelling of 12646721 in words is "twelve million, six hundred forty-six thousand, seven hundred twenty-one".