13728521 has 4 divisors (see below), whose sum is σ = 13739844. Its totient is φ = 13717200.

The previous prime is 13728511. The next prime is 13728529. The reversal of 13728521 is 12582731.

13728521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 1860496 + 11868025 = 1364^2 + 3445^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-13728521 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (13728529) 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, 3590 + ... + 6351.

It is an arithmetic number, because the mean of its divisors is an integer number (3434961).

Almost surely, 2^13728521 is an apocalyptic number.

It is an amenable number.

13728521 is a deficient number, since it is larger than the sum of its proper divisors (11323).

13728521 is an equidigital number, since it uses as much as digits as its factorization.

13728521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11322.

The product of its digits is 3360, while the sum is 29.

The square root of 13728521 is about 3705.2018838385. The cubic root of 13728521 is about 239.4461824995.

The spelling of 13728521 in words is "thirteen million, seven hundred twenty-eight thousand, five hundred twenty-one".