664081393 has 2 divisors, whose sum is σ = 664081394. Its totient is φ = 664081392.

The previous prime is 664081391. The next prime is 664081409. The reversal of 664081393 is 393180466.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644296689 + 19784704 = 25383^2 + 4448^2 .

It is a cyclic number.

It is not a de Polignac number, because 664081393 - 2¹ = 664081391 is a prime.

Together with 664081391, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (664081391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332040696 + 332040697.

It is an arithmetic number, because the mean of its divisors is an integer number (332040697).

Almost surely, 2^664081393 is an apocalyptic number.

It is an amenable number.

664081393 is a deficient number, since it is larger than the sum of its proper divisors (1).

664081393 is an equidigital number, since it uses as much as digits as its factorization.

664081393 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 93312, while the sum is 40.

The square root of 664081393 is about 25769.7767355482. The cubic root of 664081393 is about 872.4497796235.

The spelling of 664081393 in words is "six hundred sixty-four million, eighty-one thousand, three hundred ninety-three".