213121111121221 has 4 divisors (see below), whose sum is σ = 213155804454912. Its totient is φ = 213086417787532.

The previous prime is 213121111121167. The next prime is 213121111121279. The reversal of 213121111121221 is 122121111121312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 213121111121221 - 2²⁷ = 213120976903493 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 213121111121192 and 213121111121201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213121411121221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17346657631 + ... + 17346669916.

It is an arithmetic number, because the mean of its divisors is an integer number (53288951113728).

Almost surely, 2^{213121111121221} is an apocalyptic number.

It is an amenable number.

213121111121221 is a deficient number, since it is larger than the sum of its proper divisors (34693333691).

213121111121221 is an equidigital number, since it uses as much as digits as its factorization.

213121111121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34693333690.

The product of its digits is 96, while the sum is 22.

Adding to 213121111121221 its reverse (122121111121312), we get a palindrome (335242222242533).

Subtracting from 213121111121221 its reverse (122121111121312), we obtain a palindrome (90999999999909).

The spelling of 213121111121221 in words is "two hundred thirteen trillion, one hundred twenty-one billion, one hundred eleven million, one hundred twenty-one thousand, two hundred twenty-one".