21223423 has 4 divisors (see below), whose sum is σ = 22856008. Its totient is φ = 19590840.

The previous prime is 21223409. The next prime is 21223427. The reversal of 21223423 is 32432212.

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 21223423 - 2¹³ = 21215231 is a prime.

It is a Duffinian number.

It is a zygodrome in base 4.

It is a self number, because there is not a number n which added to its sum of digits gives 21223423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21223427) 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, 816273 + ... + 816298.

It is an arithmetic number, because the mean of its divisors is an integer number (5714002).

Almost surely, 2^21223423 is an apocalyptic number.

21223423 is a deficient number, since it is larger than the sum of its proper divisors (1632585).

21223423 is a wasteful number, since it uses less digits than its factorization.

21223423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1632584.

The product of its digits is 576, while the sum is 19.

The square root of 21223423 is about 4606.8886463643. Note that the first 3 decimals coincide. The cubic root of 21223423 is about 276.8673921174.

Adding to 21223423 its reverse (32432212), we get a palindrome (53655635).

The spelling of 21223423 in words is "twenty-one million, two hundred twenty-three thousand, four hundred twenty-three".