21222012121 has 4 divisors (see below), whose sum is σ = 21409817652. Its totient is φ = 21034206592.

The previous prime is 21222012113. The next prime is 21222012127. The reversal of 21222012121 is 12121022212.

It is a happy number.

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 2506404096 + 18715608025 = 50064^2 + 136805^2 .

It is a cyclic number.

It is not a de Polignac number, because 21222012121 - 2³ = 21222012113 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21222012095 and 21222012104.

It is not an unprimeable number, because it can be changed into a prime (21222012127) 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, 93902596 + ... + 93902821.

It is an arithmetic number, because the mean of its divisors is an integer number (5352454413).

Almost surely, 2^21222012121 is an apocalyptic number.

It is an amenable number.

21222012121 is a deficient number, since it is larger than the sum of its proper divisors (187805531).

21222012121 is a wasteful number, since it uses less digits than its factorization.

21222012121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187805530.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21222012121 its reverse (12121022212), we get a palindrome (33343034333).

The spelling of 21222012121 in words is "twenty-one billion, two hundred twenty-two million, twelve thousand, one hundred twenty-one".