13521 has 4 divisors (see below), whose sum is σ = 18032. Its totient is φ = 9012.

The previous prime is 13513. The next prime is 13523. The reversal of 13521 is 12531.

13521 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

13521 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12531 = 3 ⋅4177.

It is not a de Polignac number, because 13521 - 2³ = 13513 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 13497 and 13506.

It is not an unprimeable number, because it can be changed into a prime (13523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2251 + ... + 2256.

It is an arithmetic number, because the mean of its divisors is an integer number (4508).

2¹³⁵²¹ is an apocalyptic number.

It is an amenable number.

13521 is a deficient number, since it is larger than the sum of its proper divisors (4511).

13521 is an equidigital number, since it uses as much as digits as its factorization.

13521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4510.

The product of its digits is 30, while the sum is 12.

The square root of 13521 is about 116.2798348812. The cubic root of 13521 is about 23.8233558358.

Subtracting from 13521 its reverse (12531), we obtain a triangular number (990 = T₄₄).

The spelling of 13521 in words is "thirteen thousand, five hundred twenty-one".