21204343221 has 8 divisors (see below), whose sum is σ = 29247370080. Its totient is φ = 13648772592.

The previous prime is 21204343217. The next prime is 21204343249. The reversal of 21204343221 is 12234340212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21204343221 - 2² = 21204343217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21204343191 and 21204343200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204343211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 121863955 + ... + 121864128.

It is an arithmetic number, because the mean of its divisors is an integer number (3655921260).

Almost surely, 2^21204343221 is an apocalyptic number.

It is an amenable number.

21204343221 is a deficient number, since it is larger than the sum of its proper divisors (8043026859).

21204343221 is a wasteful number, since it uses less digits than its factorization.

21204343221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243728115.

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

Adding to 21204343221 its reverse (12234340212), we get a palindrome (33438683433).

The spelling of 21204343221 in words is "twenty-one billion, two hundred four million, three hundred forty-three thousand, two hundred twenty-one".