6441605221 has 2 divisors, whose sum is σ = 6441605222. Its totient is φ = 6441605220.

The previous prime is 6441605173. The next prime is 6441605237. The reversal of 6441605221 is 1225061446.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5792884321 + 648720900 = 76111^2 + 25470^2 .

It is a cyclic number.

It is not a de Polignac number, because 6441605221 - 2²¹ = 6439508069 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6441609221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3220802610 + 3220802611.

It is an arithmetic number, because the mean of its divisors is an integer number (3220802611).

Almost surely, 2^6441605221 is an apocalyptic number.

It is an amenable number.

6441605221 is a deficient number, since it is larger than the sum of its proper divisors (1).

6441605221 is an equidigital number, since it uses as much as digits as its factorization.

6441605221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 31.

The square root of 6441605221 is about 80259.6113932780. The cubic root of 6441605221 is about 1860.6500619268.

Adding to 6441605221 its reverse (1225061446), we get a palindrome (7666666667).

The spelling of 6441605221 in words is "six billion, four hundred forty-one million, six hundred five thousand, two hundred twenty-one".