23921 has 4 divisors (see below), whose sum is σ = 25200. Its totient is φ = 22644.

The previous prime is 23917. The next prime is 23929. The reversal of 23921 is 12932.

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 23921 - 2² = 23917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 23921.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 23921.

It is not an unprimeable number, because it can be changed into a prime (23929) 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, 611 + ... + 648.

It is an arithmetic number, because the mean of its divisors is an integer number (6300).

2²³⁹²¹ is an apocalyptic number.

It is an amenable number.

23921 is a deficient number, since it is larger than the sum of its proper divisors (1279).

23921 is a wasteful number, since it uses less digits than its factorization.

23921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1278.

The product of its digits is 108, while the sum is 17.

The square root of 23921 is about 154.6641522784. The cubic root of 23921 is about 28.8133072505.

The spelling of 23921 in words is "twenty-three thousand, nine hundred twenty-one".