21321222121 has 4 divisors (see below), whose sum is σ = 21367877332. Its totient is φ = 21274566912.

The previous prime is 21321222101. The next prime is 21321222133. The reversal of 21321222121 is 12122212312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6978764521 + 14342457600 = 83539^2 + 119760^2 .

It is a cyclic number.

It is not a de Polignac number, because 21321222121 - 2¹³ = 21321213929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21321222101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23326920 + ... + 23327833.

It is an arithmetic number, because the mean of its divisors is an integer number (5341969333).

Almost surely, 2^21321222121 is an apocalyptic number.

It is an amenable number.

21321222121 is a deficient number, since it is larger than the sum of its proper divisors (46655211).

21321222121 is an equidigital number, since it uses as much as digits as its factorization.

21321222121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46655210.

The product of its digits is 192, while the sum is 19.

Adding to 21321222121 its reverse (12122212312), we get a palindrome (33443434433).

The spelling of 21321222121 in words is "twenty-one billion, three hundred twenty-one million, two hundred twenty-two thousand, one hundred twenty-one".