213131221 has 8 divisors (see below), whose sum is σ = 218234304. Its totient is φ = 208084800.

The previous prime is 213131209. The next prime is 213131249. The reversal of 213131221 is 122131312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 213131221 - 2¹¹ = 213129173 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 213131195 and 213131204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (213131291) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6505 + ... + 21646.

It is an arithmetic number, because the mean of its divisors is an integer number (27279288).

Almost surely, 2^213131221 is an apocalyptic number.

It is an amenable number.

213131221 is a deficient number, since it is larger than the sum of its proper divisors (5103083).

213131221 is a wasteful number, since it uses less digits than its factorization.

213131221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28331.

The product of its digits is 72, while the sum is 16.

The square root of 213131221 is about 14599.0143845398. The cubic root of 213131221 is about 597.3318759251.

Adding to 213131221 its reverse (122131312), we get a palindrome (335262533).

Subtracting from 213131221 its reverse (122131312), we obtain a palindrome (90999909).

The spelling of 213131221 in words is "two hundred thirteen million, one hundred thirty-one thousand, two hundred twenty-one".