221131221 has 4 divisors (see below), whose sum is σ = 294841632. Its totient is φ = 147420812.

The previous prime is 221131219. The next prime is 221131231. The reversal of 221131221 is 122131122.

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 221131221 - 2¹ = 221131219 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221131221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221131201) 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, 36855201 + ... + 36855206.

It is an arithmetic number, because the mean of its divisors is an integer number (73710408).

Almost surely, 2^221131221 is an apocalyptic number.

It is an amenable number.

221131221 is a deficient number, since it is larger than the sum of its proper divisors (73710411).

221131221 is an equidigital number, since it uses as much as digits as its factorization.

221131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73710410.

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

The square root of 221131221 is about 14870.4815322168. The cubic root of 221131221 is about 604.7139972778.

Adding to 221131221 its reverse (122131122), we get a palindrome (343262343).

Subtracting from 221131221 its reverse (122131122), we obtain a palindrome (99000099).

The spelling of 221131221 in words is "two hundred twenty-one million, one hundred thirty-one thousand, two hundred twenty-one".