21022222121 has 4 divisors (see below), whose sum is σ = 21025499472. Its totient is φ = 21018944772.

The previous prime is 21022222033. The next prime is 21022222129. The reversal of 21022222121 is 12122222012.

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 a de Polignac number, because none of the positive numbers 2^k-21022222121 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21022222121.

It is not an unprimeable number, because it can be changed into a prime (21022222129) 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, 1629035 + ... + 1641888.

It is an arithmetic number, because the mean of its divisors is an integer number (5256374868).

Almost surely, 2^21022222121 is an apocalyptic number.

It is an amenable number.

21022222121 is a deficient number, since it is larger than the sum of its proper divisors (3277351).

21022222121 is an equidigital number, since it uses as much as digits as its factorization.

21022222121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3277350.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21022222121 its reverse (12122222012), we get a palindrome (33144444133).

The spelling of 21022222121 in words is "twenty-one billion, twenty-two million, two hundred twenty-two thousand, one hundred twenty-one".