13278721 has 2 divisors, whose sum is σ = 13278722. Its totient is φ = 13278720.

The previous prime is 13278719. The next prime is 13278737. The reversal of 13278721 is 12787231.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11560000 + 1718721 = 3400^2 + 1311^2 .

It is a cyclic number.

It is not a de Polignac number, because 13278721 - 2¹ = 13278719 is a prime.

Together with 13278719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (13278791) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6639360 + 6639361.

It is an arithmetic number, because the mean of its divisors is an integer number (6639361).

Almost surely, 2^13278721 is an apocalyptic number.

It is an amenable number.

13278721 is a deficient number, since it is larger than the sum of its proper divisors (1).

13278721 is an equidigital number, since it uses as much as digits as its factorization.

13278721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4704, while the sum is 31.

The square root of 13278721 is about 3643.9979418216. The cubic root of 13278721 is about 236.8020268670.

The spelling of 13278721 in words is "thirteen million, two hundred seventy-eight thousand, seven hundred twenty-one".