4431221321 has 2 divisors, whose sum is σ = 4431221322. Its totient is φ = 4431221320.

The previous prime is 4431221317. The next prime is 4431221359. The reversal of 4431221321 is 1231221344.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4427039296 + 4182025 = 66536^2 + 2045^2 .

It is a cyclic number.

It is not a de Polignac number, because 4431221321 - 2² = 4431221317 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (4431221621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2215610660 + 2215610661.

It is an arithmetic number, because the mean of its divisors is an integer number (2215610661).

Almost surely, 2^4431221321 is an apocalyptic number.

It is an amenable number.

4431221321 is a deficient number, since it is larger than the sum of its proper divisors (1).

4431221321 is an equidigital number, since it uses as much as digits as its factorization.

4431221321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1152, while the sum is 23.

The square root of 4431221321 is about 66567.4193656326. The cubic root of 4431221321 is about 1642.5092118003.

Adding to 4431221321 its sum of digits (23), we get a palindrome (4431221344).

Adding to 4431221321 its reverse (1231221344), we get a palindrome (5662442665).

The spelling of 4431221321 in words is "four billion, four hundred thirty-one million, two hundred twenty-one thousand, three hundred twenty-one".