23440 has 20 divisors (see below), whose sum is σ = 54684. Its totient is φ = 9344.

The previous prime is 23431. The next prime is 23447. The reversal of 23440 is 4432.

It can be written as a sum of positive squares in 2 ways, for example, as 16384 + 7056 = 128^2 + 84^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a plaindrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 23440.

It is not an unprimeable number, because it can be changed into a prime (23447) 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, 67 + ... + 226.

2²³⁴⁴⁰ is an apocalyptic number.

23440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

23440 is an abundant number, since it is smaller than the sum of its proper divisors (31244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27342).

23440 is a wasteful number, since it uses less digits than its factorization.

23440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306 (or 300 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 13.

The square root of 23440 is about 153.1012736720. The cubic root of 23440 is about 28.6188735514.

Adding to 23440 its reverse (4432), we get a palindrome (27872).

The spelling of 23440 in words is "twenty-three thousand, four hundred forty", and thus it is an iban number.