221321213 has 4 divisors (see below), whose sum is σ = 225072480. Its totient is φ = 217569948.

The previous prime is 221321209. The next prime is 221321251. The reversal of 221321213 is 312123122.

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 221321213 - 2² = 221321209 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 221321191 and 221321200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221321273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1875545 + ... + 1875662.

It is an arithmetic number, because the mean of its divisors is an integer number (56268120).

Almost surely, 2^221321213 is an apocalyptic number.

It is an amenable number.

221321213 is a deficient number, since it is larger than the sum of its proper divisors (3751267).

221321213 is an equidigital number, since it uses as much as digits as its factorization.

221321213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3751266.

The product of its digits is 144, while the sum is 17.

The square root of 221321213 is about 14876.8683868615. The cubic root of 221321213 is about 604.8871341946.

Adding to 221321213 its reverse (312123122), we get a palindrome (533444335).

The spelling of 221321213 in words is "two hundred twenty-one million, three hundred twenty-one thousand, two hundred thirteen".