664838639609 has 2 divisors, whose sum is σ = 664838639610. Its totient is φ = 664838639608.

The previous prime is 664838639579. The next prime is 664838639611. The reversal of 664838639609 is 906936838466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 473064713209 + 191773926400 = 687797^2 + 437920^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664838639609 is a prime.

Together with 664838639611, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (664838639629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332419319804 + 332419319805.

It is an arithmetic number, because the mean of its divisors is an integer number (332419319805).

Almost surely, 2^664838639609 is an apocalyptic number.

It is an amenable number.

664838639609 is a deficient number, since it is larger than the sum of its proper divisors (1).

664838639609 is an equidigital number, since it uses as much as digits as its factorization.

664838639609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 241864704, while the sum is 68.

The spelling of 664838639609 in words is "six hundred sixty-four billion, eight hundred thirty-eight million, six hundred thirty-nine thousand, six hundred nine".