21440523 has 16 divisors (see below), whose sum is σ = 30978080. Its totient is φ = 13190112.

The previous prime is 21440491. The next prime is 21440527. The reversal of 21440523 is 32504412.

It is not a de Polignac number, because 21440523 - 2⁵ = 21440491 is a prime.

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 21440523.

It is not an unprimeable number, because it can be changed into a prime (21440527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4965 + ... + 8217.

It is an arithmetic number, because the mean of its divisors is an integer number (1936130).

Almost surely, 2^21440523 is an apocalyptic number.

21440523 is a deficient number, since it is larger than the sum of its proper divisors (9537557).

21440523 is an equidigital number, since it uses as much as digits as its factorization.

21440523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3295 (or 3269 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21440523 is about 4630.3912361700. The cubic root of 21440523 is about 277.8082412042.

Adding to 21440523 its reverse (32504412), we get a palindrome (53944935).

The spelling of 21440523 in words is "twenty-one million, four hundred forty thousand, five hundred twenty-three".