664113521 has 2 divisors, whose sum is σ = 664113522. Its totient is φ = 664113520.

The previous prime is 664113497. The next prime is 664113529. The reversal of 664113521 is 125311466.

It is a happy number.

664113521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 424978225 + 239135296 = 20615^2 + 15464^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664113521 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (664113529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332056760 + 332056761.

It is an arithmetic number, because the mean of its divisors is an integer number (332056761).

Almost surely, 2^664113521 is an apocalyptic number.

It is an amenable number.

664113521 is a deficient number, since it is larger than the sum of its proper divisors (1).

664113521 is an equidigital number, since it uses as much as digits as its factorization.

664113521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 29.

The square root of 664113521 is about 25770.4000939062. The cubic root of 664113521 is about 872.4638489905.

Adding to 664113521 its reverse (125311466), we get a palindrome (789424987).

The spelling of 664113521 in words is "six hundred sixty-four million, one hundred thirteen thousand, five hundred twenty-one".