221304221 has 4 divisors (see below), whose sum is σ = 225055200. Its totient is φ = 217553244.

The previous prime is 221304211. The next prime is 221304253. The reversal of 221304221 is 122403122.

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 a de Polignac number, because none of the positive numbers 2^k-221304221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 221304221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221304211) 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, 1875401 + ... + 1875518.

It is an arithmetic number, because the mean of its divisors is an integer number (56263800).

Almost surely, 2^221304221 is an apocalyptic number.

It is an amenable number.

221304221 is a deficient number, since it is larger than the sum of its proper divisors (3750979).

221304221 is an equidigital number, since it uses as much as digits as its factorization.

221304221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3750978.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 221304221 is about 14876.2972879679. The cubic root of 221304221 is about 604.8716536703.

Adding to 221304221 its reverse (122403122), we get a palindrome (343707343).

The spelling of 221304221 in words is "two hundred twenty-one million, three hundred four thousand, two hundred twenty-one".