23521 has 4 divisors (see below), whose sum is σ = 24112. Its totient is φ = 22932.

The previous prime is 23509. The next prime is 23531. The reversal of 23521 is 12532.

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 23521 - 2¹³ = 15329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (23531) 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, 231 + ... + 316.

It is an arithmetic number, because the mean of its divisors is an integer number (6028).

2²³⁵²¹ is an apocalyptic number.

It is an amenable number.

23521 is a deficient number, since it is larger than the sum of its proper divisors (591).

23521 is an equidigital number, since it uses as much as digits as its factorization.

23521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 590.

The product of its digits is 60, while the sum is 13.

The square root of 23521 is about 153.3655763201. The cubic root of 23521 is about 28.6518010781.

It can be divided in two parts, 235 and 21, that added together give a 8-th power (256 = 2⁸).

The spelling of 23521 in words is "twenty-three thousand, five hundred twenty-one".