13391721 has 24 divisors (see below), whose sum is σ = 22823424. Its totient is φ = 7404480.

The previous prime is 13391711. The next prime is 13391731. The reversal of 13391721 is 12719331.

It is an interprime number because it is at equal distance from previous prime (13391711) and next prime (13391731).

It is not a de Polignac number, because 13391721 - 2⁵ = 13391689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (13391701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1476 + ... + 5381.

It is an arithmetic number, because the mean of its divisors is an integer number (950976).

Almost surely, 2^13391721 is an apocalyptic number.

It is an amenable number.

13391721 is a deficient number, since it is larger than the sum of its proper divisors (9431703).

13391721 is a wasteful number, since it uses less digits than its factorization.

13391721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6901 (or 6898 counting only the distinct ones).

The product of its digits is 1134, while the sum is 27.

The square root of 13391721 is about 3659.4700435992. The cubic root of 13391721 is about 237.4718474479.

The spelling of 13391721 in words is "thirteen million, three hundred ninety-one thousand, seven hundred twenty-one".