21624423 has 4 divisors (see below), whose sum is σ = 28832568. Its totient is φ = 14416280.

The previous prime is 21624409. The next prime is 21624443. The reversal of 21624423 is 32442612.

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

It is a cyclic number.

It is not a de Polignac number, because 21624423 - 2⁶ = 21624359 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21624393 and 21624402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21624443) 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, 3604068 + ... + 3604073.

It is an arithmetic number, because the mean of its divisors is an integer number (7208142).

Almost surely, 2^21624423 is an apocalyptic number.

21624423 is a deficient number, since it is larger than the sum of its proper divisors (7208145).

21624423 is an equidigital number, since it uses as much as digits as its factorization.

21624423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7208144.

The product of its digits is 2304, while the sum is 24.

The square root of 21624423 is about 4650.2067695964. The cubic root of 21624423 is about 278.6002548549.

The spelling of 21624423 in words is "twenty-one million, six hundred twenty-four thousand, four hundred twenty-three".