23809 has 4 divisors (see below), whose sum is σ = 24660. Its totient is φ = 22960.

The previous prime is 23801. The next prime is 23813. The reversal of 23809 is 90832.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9409 + 14400 = 97^2 + 120^2 .

It is a cyclic number.

It is not a de Polignac number, because 23809 - 2³ = 23801 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 23809.

It is not an unprimeable number, because it can be changed into a prime (23801) 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, 382 + ... + 439.

It is an arithmetic number, because the mean of its divisors is an integer number (6165).

It is a Proth number, since it is equal to 93 ⋅ 2⁸ + 1 and 93 < 2⁸.

2²³⁸⁰⁹ is an apocalyptic number.

23809 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

23809 is a deficient number, since it is larger than the sum of its proper divisors (851).

23809 is an equidigital number, since it uses as much as digits as its factorization.

23809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 850.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 23809 is about 154.3016526159. The cubic root of 23809 is about 28.7682681628.

The spelling of 23809 in words is "twenty-three thousand, eight hundred nine".