21212021121 has 16 divisors (see below), whose sum is σ = 28364878080. Its totient is φ = 14100302720.

The previous prime is 21212021071. The next prime is 21212021123. The reversal of 21212021121 is 12112021212.

It is a cyclic number.

It is not a de Polignac number, because 21212021121 - 2³⁰ = 20138279297 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21212021121.

It is not an unprimeable number, because it can be changed into a prime (21212021123) 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, 2184445 + ... + 2194133.

It is an arithmetic number, because the mean of its divisors is an integer number (1772804880).

Almost surely, 2^21212021121 is an apocalyptic number.

It is an amenable number.

21212021121 is a deficient number, since it is larger than the sum of its proper divisors (7152856959).

21212021121 is a wasteful number, since it uses less digits than its factorization.

21212021121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11736.

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

Adding to 21212021121 its reverse (12112021212), we get a palindrome (33324042333).

Subtracting from 21212021121 its reverse (12112021212), we obtain a palindrome (9099999909).

The spelling of 21212021121 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, one hundred twenty-one".