13397721 has 4 divisors (see below), whose sum is σ = 17863632. Its totient is φ = 8931812.

The previous prime is 13397719. The next prime is 13397729. The reversal of 13397721 is 12779331.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 13397721 - 2¹ = 13397719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (13397729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2232951 + ... + 2232956.

It is an arithmetic number, because the mean of its divisors is an integer number (4465908).

Almost surely, 2^13397721 is an apocalyptic number.

It is an amenable number.

13397721 is a deficient number, since it is larger than the sum of its proper divisors (4465911).

13397721 is an equidigital number, since it uses as much as digits as its factorization.

13397721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4465910.

The product of its digits is 7938, while the sum is 33.

The square root of 13397721 is about 3660.2897426297. The cubic root of 13397721 is about 237.5073076237.

The spelling of 13397721 in words is "thirteen million, three hundred ninety-seven thousand, seven hundred twenty-one".