665789 has 2 divisors, whose sum is σ = 665790. Its totient is φ = 665788.

The previous prime is 665783. The next prime is 665801. The reversal of 665789 is 987566.

It is a happy number.

665789 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 444889 + 220900 = 667^2 + 470^2 .

It is a cyclic number.

It is not a de Polignac number, because 665789 - 2⁴ = 665773 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 (665783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332894 + 332895.

It is an arithmetic number, because the mean of its divisors is an integer number (332895).

2⁶⁶⁵⁷⁸⁹ is an apocalyptic number.

It is an amenable number.

665789 is a deficient number, since it is larger than the sum of its proper divisors (1).

665789 is an equidigital number, since it uses as much as digits as its factorization.

665789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 41.

The square root of 665789 is about 815.9589450456. The cubic root of 665789 is about 87.3196940156.

The spelling of 665789 in words is "six hundred sixty-five thousand, seven hundred eighty-nine".