221231321 has 2 divisors, whose sum is σ = 221231322. Its totient is φ = 221231320.

The previous prime is 221231293. The next prime is 221231327. The reversal of 221231321 is 123132122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 157151296 + 64080025 = 12536^2 + 8005^2 .

It is a cyclic number.

It is not a de Polignac number, because 221231321 - 2¹⁰ = 221230297 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221231321.

It is not a weakly prime, because it can be changed into another prime (221231327) 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 as a sum of consecutive naturals, namely, 110615660 + 110615661.

It is an arithmetic number, because the mean of its divisors is an integer number (110615661).

Almost surely, 2^221231321 is an apocalyptic number.

It is an amenable number.

221231321 is a deficient number, since it is larger than the sum of its proper divisors (1).

221231321 is an equidigital number, since it uses as much as digits as its factorization.

221231321 is an odious number, because the sum of its binary digits is odd.

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

The square root of 221231321 is about 14873.8468796744. The cubic root of 221231321 is about 604.8052292915.

Adding to 221231321 its reverse (123132122), we get a palindrome (344363443).

It can be divided in two parts, 2212 and 31321, that added together give a palindrome (33533).

The spelling of 221231321 in words is "two hundred twenty-one million, two hundred thirty-one thousand, three hundred twenty-one".