21211022121 has 16 divisors (see below), whose sum is σ = 28888005888. Its totient is φ = 13837462400.

The previous prime is 21211022113. The next prime is 21211022141. The reversal of 21211022121 is 12122011212.

It is a cyclic number.

It is not a de Polignac number, because 21211022121 - 2³ = 21211022113 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21211022121.

It is not an unprimeable number, because it can be changed into a prime (21211022141) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1283491 + ... + 1299911.

It is an arithmetic number, because the mean of its divisors is an integer number (1805500368).

Almost surely, 2^21211022121 is an apocalyptic number.

It is an amenable number.

21211022121 is a deficient number, since it is larger than the sum of its proper divisors (7676983767).

21211022121 is a wasteful number, since it uses less digits than its factorization.

21211022121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25632.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21211022121 its reverse (12122011212), we get a palindrome (33333033333).

The spelling of 21211022121 in words is "twenty-one billion, two hundred eleven million, twenty-two thousand, one hundred twenty-one".