21331211121 has 36 divisors (see below), whose sum is σ = 34216778596. Its totient is φ = 12794664960.

The previous prime is 21331211117. The next prime is 21331211123. The reversal of 21331211121 is 12111213312.

21331211121 is a `hidden beast` number, since 2 + 1 + 331 + 211 + 121 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 13855879521 + 7475331600 = 117711^2 + 86460^2 .

It is not a de Polignac number, because 21331211121 - 2² = 21331211117 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21331211094 and 21331211103.

It is not an unprimeable number, because it can be changed into a prime (21331211123) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 4665 + ... + 206601.

Almost surely, 2^21331211121 is an apocalyptic number.

It is an amenable number.

21331211121 is a deficient number, since it is larger than the sum of its proper divisors (12885567475).

21331211121 is a wasteful number, since it uses less digits than its factorization.

21331211121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 202062 (or 202048 counting only the distinct ones).

The product of its digits is 72, while the sum is 18.

Adding to 21331211121 its reverse (12111213312), we get a palindrome (33442424433).

The spelling of 21331211121 in words is "twenty-one billion, three hundred thirty-one million, two hundred eleven thousand, one hundred twenty-one".