23213521 has 4 divisors (see below), whose sum is σ = 23540544. Its totient is φ = 22886500.

The previous prime is 23213479. The next prime is 23213527. The reversal of 23213521 is 12531232.

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 23213521 - 2¹⁵ = 23180753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (23213527) 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, 163405 + ... + 163546.

It is an arithmetic number, because the mean of its divisors is an integer number (5885136).

Almost surely, 2^23213521 is an apocalyptic number.

It is an amenable number.

23213521 is a deficient number, since it is larger than the sum of its proper divisors (327023).

23213521 is an equidigital number, since it uses as much as digits as its factorization.

23213521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327022.

The product of its digits is 360, while the sum is 19.

The square root of 23213521 is about 4818.0411994918. The cubic root of 23213521 is about 285.2640253619.

Adding to 23213521 its reverse (12531232), we get a palindrome (35744753).

The spelling of 23213521 in words is "twenty-three million, two hundred thirteen thousand, five hundred twenty-one".