664328515421 has 2 divisors, whose sum is σ = 664328515422. Its totient is φ = 664328515420.

The previous prime is 664328515397. The next prime is 664328515451. The reversal of 664328515421 is 124515823466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 624613605625 + 39714909796 = 790325^2 + 199286^2 .

It is a cyclic number.

It is not a de Polignac number, because 664328515421 - 2²² = 664324321117 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664328515451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332164257710 + 332164257711.

It is an arithmetic number, because the mean of its divisors is an integer number (332164257711).

Almost surely, 2^664328515421 is an apocalyptic number.

It is an amenable number.

664328515421 is a deficient number, since it is larger than the sum of its proper divisors (1).

664328515421 is an equidigital number, since it uses as much as digits as its factorization.

664328515421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1382400, while the sum is 47.

The spelling of 664328515421 in words is "six hundred sixty-four billion, three hundred twenty-eight million, five hundred fifteen thousand, four hundred twenty-one".