21423204423 has 24 divisors (see below), whose sum is σ = 32263795200. Its totient is φ = 13681047744.

The previous prime is 21423204409. The next prime is 21423204493. The reversal of 21423204423 is 32440232412.

21423204423 is a `hidden beast` number, since 2 + 1 + 4 + 232 + 0 + 4 + 423 = 666.

It is not a de Polignac number, because 21423204423 - 2¹⁶ = 21423138887 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21423204493) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 290008 + ... + 356301.

It is an arithmetic number, because the mean of its divisors is an integer number (1344324800).

Almost surely, 2^21423204423 is an apocalyptic number.

21423204423 is a deficient number, since it is larger than the sum of its proper divisors (10840590777).

21423204423 is a wasteful number, since it uses less digits than its factorization.

21423204423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 646471 (or 646468 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 27.

Adding to 21423204423 its reverse (32440232412), we get a palindrome (53863436835).

The spelling of 21423204423 in words is "twenty-one billion, four hundred twenty-three million, two hundred four thousand, four hundred twenty-three".