665438789 has 2 divisors, whose sum is σ = 665438790. Its totient is φ = 665438788.

The previous prime is 665438743. The next prime is 665438801. The reversal of 665438789 is 987834566.

665438789 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., 643890625 + 21548164 = 25375^2 + 4642^2 .

It is a cyclic number.

It is not a de Polignac number, because 665438789 - 2⁸ = 665438533 is a prime.

It is a Sophie Germain prime.

It is a Chen 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 (665438489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332719394 + 332719395.

It is an arithmetic number, because the mean of its divisors is an integer number (332719395).

Almost surely, 2^665438789 is an apocalyptic number.

It is an amenable number.

665438789 is a deficient number, since it is larger than the sum of its proper divisors (1).

665438789 is an equidigital number, since it uses as much as digits as its factorization.

665438789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8709120, while the sum is 56.

The square root of 665438789 is about 25796.1002672885. The cubic root of 665438789 is about 873.0438101569.

The spelling of 665438789 in words is "six hundred sixty-five million, four hundred thirty-eight thousand, seven hundred eighty-nine".