665856589 has 2 divisors, whose sum is σ = 665856590. Its totient is φ = 665856588.

The previous prime is 665856571. The next prime is 665856623. The reversal of 665856589 is 985658566.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 445927689 + 219928900 = 21117^2 + 14830^2 .

It is a cyclic number.

It is not a de Polignac number, because 665856589 - 2⁵ = 665856557 is a prime.

It is a super-2 number, since 2×665856589² = 886729994229429842, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665856689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332928294 + 332928295.

It is an arithmetic number, because the mean of its divisors is an integer number (332928295).

Almost surely, 2^665856589 is an apocalyptic number.

It is an amenable number.

665856589 is a deficient number, since it is larger than the sum of its proper divisors (1).

665856589 is an equidigital number, since it uses as much as digits as its factorization.

665856589 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552000, while the sum is 58.

The square root of 665856589 is about 25804.1971198485. The cubic root of 665856589 is about 873.2264873107.

The spelling of 665856589 in words is "six hundred sixty-five million, eight hundred fifty-six thousand, five hundred eighty-nine".