21000222121 has 4 divisors (see below), whose sum is σ = 21003616000. Its totient is φ = 20996828244.

The previous prime is 21000222101. The next prime is 21000222211. The reversal of 21000222121 is 12122200012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21000222121 - 2¹³ = 21000213929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21000222101) 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, 1687641 + ... + 1700038.

It is an arithmetic number, because the mean of its divisors is an integer number (5250904000).

Almost surely, 2^21000222121 is an apocalyptic number.

It is an amenable number.

21000222121 is a deficient number, since it is larger than the sum of its proper divisors (3393879).

21000222121 is an equidigital number, since it uses as much as digits as its factorization.

21000222121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3393878.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21000222121 its reverse (12122200012), we get a palindrome (33122422133).

The spelling of 21000222121 in words is "twenty-one billion, two hundred twenty-two thousand, one hundred twenty-one".