21504423 has 8 divisors (see below), whose sum is σ = 28844928. Its totient is φ = 14250104.

The previous prime is 21504403. The next prime is 21504433. The reversal of 21504423 is 32440512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21504423 - 2¹⁰ = 21503399 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21504423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21504403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20961 + ... + 21962.

It is an arithmetic number, because the mean of its divisors is an integer number (3605616).

Almost surely, 2^21504423 is an apocalyptic number.

21504423 is a deficient number, since it is larger than the sum of its proper divisors (7340505).

21504423 is a wasteful number, since it uses less digits than its factorization.

21504423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43093.

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

The square root of 21504423 is about 4637.2861675769. The cubic root of 21504423 is about 278.0839549412.

Adding to 21504423 its reverse (32440512), we get a palindrome (53944935).

The spelling of 21504423 in words is "twenty-one million, five hundred four thousand, four hundred twenty-three".