664640437 has 2 divisors, whose sum is σ = 664640438. Its totient is φ = 664640436.

The previous prime is 664640419. The next prime is 664640447. The reversal of 664640437 is 734046466.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 664041361 + 599076 = 25769^2 + 774^2 .

It is a cyclic number.

It is not a de Polignac number, because 664640437 - 2⁷ = 664640309 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 664640437.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664640447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332320218 + 332320219.

It is an arithmetic number, because the mean of its divisors is an integer number (332320219).

Almost surely, 2^664640437 is an apocalyptic number.

It is an amenable number.

664640437 is a deficient number, since it is larger than the sum of its proper divisors (1).

664640437 is an equidigital number, since it uses as much as digits as its factorization.

664640437 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 290304, while the sum is 40.

The square root of 664640437 is about 25780.6213462748. The cubic root of 664640437 is about 872.6945292478.

The spelling of 664640437 in words is "six hundred sixty-four million, six hundred forty thousand, four hundred thirty-seven".