21121221121 has 24 divisors (see below), whose sum is σ = 28864975104. Its totient is φ = 15192082080.

The previous prime is 21121221113. The next prime is 21121221137. The reversal of 21121221121 is 12112212112.

It is not a de Polignac number, because 21121221121 - 2³ = 21121221113 is a prime.

It is a super-2 number, since 2×21121221121² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21121221095 and 21121221104.

It is not an unprimeable number, because it can be changed into a prime (21121221151) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1500145 + ... + 1514158.

It is an arithmetic number, because the mean of its divisors is an integer number (1202707296).

Almost surely, 2^21121221121 is an apocalyptic number.

It is an amenable number.

21121221121 is a deficient number, since it is larger than the sum of its proper divisors (7743753983).

21121221121 is a wasteful number, since it uses less digits than its factorization.

21121221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3014341 (or 3014334 counting only the distinct ones).

The product of its digits is 32, while the sum is 16.

Adding to 21121221121 its reverse (12112212112), we get a palindrome (33233433233).

Subtracting from 21121221121 its reverse (12112212112), we obtain a palindrome (9009009009).

It can be divided in two parts, 21121 and 221121, that added together give a palindrome (242242).

The spelling of 21121221121 in words is "twenty-one billion, one hundred twenty-one million, two hundred twenty-one thousand, one hundred twenty-one".