21122111122221 has 8 divisors (see below), whose sum is σ = 28233046289664. Its totient is φ = 14046291684800.

The previous prime is 21122111122169. The next prime is 21122111122237. The reversal of 21122111122221 is 12222111122112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21122111122221 - 2¹⁰ = 21122111121197 is a prime.

It is a super-2 number, since 2×21122111122221² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122111122271) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8778931101 + ... + 8778933506.

It is an arithmetic number, because the mean of its divisors is an integer number (3529130786208).

Almost surely, 2^{21122111122221} is an apocalyptic number.

It is an amenable number.

21122111122221 is a deficient number, since it is larger than the sum of its proper divisors (7110935167443).

21122111122221 is a wasteful number, since it uses less digits than its factorization.

21122111122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17557865011.

The product of its digits is 128, while the sum is 21.

Adding to 21122111122221 its reverse (12222111122112), we get a palindrome (33344222244333).

The spelling of 21122111122221 in words is "twenty-one trillion, one hundred twenty-two billion, one hundred eleven million, one hundred twenty-two thousand, two hundred twenty-one".