21122112221 has 16 divisors (see below), whose sum is σ = 24716689920. Its totient is φ = 17673803520.

The previous prime is 21122112217. The next prime is 21122112227. The reversal of 21122112221 is 12221122112.

It is a cyclic number.

It is not a de Polignac number, because 21122112221 - 2² = 21122112217 is a prime.

It is a super-2 number, since 2×21122112221² (a number of 21 digits) contains 22 as substring.

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 21122112221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122112227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45461 + ... + 210501.

It is an arithmetic number, because the mean of its divisors is an integer number (1544793120).

Almost surely, 2^21122112221 is an apocalyptic number.

It is an amenable number.

21122112221 is a deficient number, since it is larger than the sum of its proper divisors (3594577699).

21122112221 is a wasteful number, since it uses less digits than its factorization.

21122112221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165484.

The product of its digits is 64, while the sum is 17.

Adding to 21122112221 its reverse (12221122112), we get a palindrome (33343234333).

The spelling of 21122112221 in words is "twenty-one billion, one hundred twenty-two million, one hundred twelve thousand, two hundred twenty-one".