21212111221121 has 16 divisors (see below), whose sum is σ = 21855839917824. Its totient is φ = 20576411192064.

The previous prime is 21212111221099. The next prime is 21212111221193. The reversal of 21212111221121 is 12112211121212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21212111221121 - 2⁶ = 21212111221057 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21212111221093 and 21212111221102.

It is not an unprimeable number, because it can be changed into a prime (21212110221121) 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, 302463566 + ... + 302533688.

It is an arithmetic number, because the mean of its divisors is an integer number (1365989994864).

Almost surely, 2^{21212111221121} is an apocalyptic number.

It is an amenable number.

21212111221121 is a deficient number, since it is larger than the sum of its proper divisors (643728696703).

21212111221121 is a wasteful number, since it uses less digits than its factorization.

21212111221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127240.

The product of its digits is 64, while the sum is 20.

Adding to 21212111221121 its reverse (12112211121212), we get a palindrome (33324322342333).

Subtracting from 21212111221121 its reverse (12112211121212), we obtain a palindrome (9099900099909).

The spelling of 21212111221121 in words is "twenty-one trillion, two hundred twelve billion, one hundred eleven million, two hundred twenty-one thousand, one hundred twenty-one".