13428721 has 2 divisors, whose sum is σ = 13428722. Its totient is φ = 13428720.

The previous prime is 13428707. The next prime is 13428731. The reversal of 13428721 is 12782431.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13359025 + 69696 = 3655^2 + 264^2 .

It is an emirp because it is prime and its reverse (12782431) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13428721 is a prime.

It is equal to p₈₇₅₃₂₃ and since 13428721 and 875323 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 13428721.

It is not a weakly prime, because it can be changed into another prime (13428731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6714360 + 6714361.

It is an arithmetic number, because the mean of its divisors is an integer number (6714361).

Almost surely, 2^13428721 is an apocalyptic number.

It is an amenable number.

13428721 is a deficient number, since it is larger than the sum of its proper divisors (1).

13428721 is an equidigital number, since it uses as much as digits as its factorization.

13428721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2688, while the sum is 28.

The square root of 13428721 is about 3664.5219333496. The cubic root of 13428721 is about 237.6903500764.

The spelling of 13428721 in words is "thirteen million, four hundred twenty-eight thousand, seven hundred twenty-one".