664213321 has 2 divisors, whose sum is σ = 664213322. Its totient is φ = 664213320.

The previous prime is 664213313. The next prime is 664213337. The reversal of 664213321 is 123312466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 643383225 + 20830096 = 25365^2 + 4564^2 .

It is a cyclic number.

It is not a de Polignac number, because 664213321 - 2³ = 664213313 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 664213321.

It is not a weakly prime, because it can be changed into another prime (664213301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332106660 + 332106661.

It is an arithmetic number, because the mean of its divisors is an integer number (332106661).

Almost surely, 2^664213321 is an apocalyptic number.

It is an amenable number.

664213321 is a deficient number, since it is larger than the sum of its proper divisors (1).

664213321 is an equidigital number, since it uses as much as digits as its factorization.

664213321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 28.

The square root of 664213321 is about 25772.3363512119. The cubic root of 664213321 is about 872.5075501190.

Adding to 664213321 its reverse (123312466), we get a palindrome (787525787).

The spelling of 664213321 in words is "six hundred sixty-four million, two hundred thirteen thousand, three hundred twenty-one".