21122121121 has 16 divisors (see below), whose sum is σ = 22656449088. Its totient is φ = 19620697600.

The previous prime is 21122121103. The next prime is 21122121131. The reversal of 21122121121 is 12112122112.

It is a cyclic number.

It is not a de Polignac number, because 21122121121 - 2⁷ = 21122120993 is a prime.

It is a super-2 number, since 2×21122121121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21122121095 and 21122121104.

It is not an unprimeable number, because it can be changed into a prime (21122121101) 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, 1532541 + ... + 1546261.

It is an arithmetic number, because the mean of its divisors is an integer number (1416028068).

Almost surely, 2^21122121121 is an apocalyptic number.

It is an amenable number.

21122121121 is a deficient number, since it is larger than the sum of its proper divisors (1534327967).

21122121121 is a wasteful number, since it uses less digits than its factorization.

21122121121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14912.

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

Adding to 21122121121 its reverse (12112122112), we get a palindrome (33234243233).

Subtracting from 21122121121 its reverse (12112122112), we obtain a palindrome (9009999009).

The spelling of 21122121121 in words is "twenty-one billion, one hundred twenty-two million, one hundred twenty-one thousand, one hundred twenty-one".