213211221 has 4 divisors (see below), whose sum is σ = 284281632. Its totient is φ = 142140812.

The previous prime is 213211213. The next prime is 213211241. The reversal of 213211221 is 122112312.

213211221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 213211221 - 2³ = 213211213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 213211221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213211241) 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, 35535201 + ... + 35535206.

It is an arithmetic number, because the mean of its divisors is an integer number (71070408).

Almost surely, 2^213211221 is an apocalyptic number.

It is an amenable number.

213211221 is a deficient number, since it is larger than the sum of its proper divisors (71070411).

213211221 is an equidigital number, since it uses as much as digits as its factorization.

213211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71070410.

The product of its digits is 48, while the sum is 15.

The square root of 213211221 is about 14601.7540384709. The cubic root of 213211221 is about 597.4066038668.

Adding to 213211221 its reverse (122112312), we get a palindrome (335323533).

The spelling of 213211221 in words is "two hundred thirteen million, two hundred eleven thousand, two hundred twenty-one".