664316221 has 2 divisors, whose sum is σ = 664316222. Its totient is φ = 664316220.

The previous prime is 664316183. The next prime is 664316231. The reversal of 664316221 is 122613466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 552908196 + 111408025 = 23514^2 + 10555^2 .

It is a cyclic number.

It is not a de Polignac number, because 664316221 - 2¹¹ = 664314173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664316231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332158110 + 332158111.

It is an arithmetic number, because the mean of its divisors is an integer number (332158111).

Almost surely, 2^664316221 is an apocalyptic number.

It is an amenable number.

664316221 is a deficient number, since it is larger than the sum of its proper divisors (1).

664316221 is an equidigital number, since it uses as much as digits as its factorization.

664316221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 31.

The square root of 664316221 is about 25774.3326004768. The cubic root of 664316221 is about 872.5526041140.

Adding to 664316221 its reverse (122613466), we get a palindrome (786929687).

The spelling of 664316221 in words is "six hundred sixty-four million, three hundred sixteen thousand, two hundred twenty-one".