21204413421 has 16 divisors (see below), whose sum is σ = 29764862400. Its totient is φ = 13390334208.

The previous prime is 21204413413. The next prime is 21204413453. The reversal of 21204413421 is 12431440212.

It is not a de Polignac number, because 21204413421 - 2³ = 21204413413 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21204413391 and 21204413400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204413471) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 445255 + ... + 490571.

It is an arithmetic number, because the mean of its divisors is an integer number (1860303900).

Almost surely, 2^21204413421 is an apocalyptic number.

It is an amenable number.

21204413421 is a deficient number, since it is larger than the sum of its proper divisors (8560448979).

21204413421 is a wasteful number, since it uses less digits than its factorization.

21204413421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53548.

The product of its (nonzero) digits is 1536, while the sum is 24.

Adding to 21204413421 its reverse (12431440212), we get a palindrome (33635853633).

The spelling of 21204413421 in words is "twenty-one billion, two hundred four million, four hundred thirteen thousand, four hundred twenty-one".