21204424211 has 4 divisors (see below), whose sum is σ = 21248692800. Its totient is φ = 21160155624.

The previous prime is 21204424193. The next prime is 21204424217. The reversal of 21204424211 is 11242440212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21204424211 is a prime.

It is a super-2 number, since 2×21204424211² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21204424217) 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, 22133576 + ... + 22134533.

It is an arithmetic number, because the mean of its divisors is an integer number (5312173200).

Almost surely, 2^21204424211 is an apocalyptic number.

21204424211 is a deficient number, since it is larger than the sum of its proper divisors (44268589).

21204424211 is an equidigital number, since it uses as much as digits as its factorization.

21204424211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44268588.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21204424211 its reverse (11242440212), we get a palindrome (32446864423).

The spelling of 21204424211 in words is "twenty-one billion, two hundred four million, four hundred twenty-four thousand, two hundred eleven".