665858 has 6 divisors (see below), whose sum is σ = 1000521. Its totient is φ = 332352.

The previous prime is 665857. The next prime is 665897. The reversal of 665858 is 858566.

It can be written as a sum of positive squares in 2 ways, for example, as 388129 + 277729 = 623^2 + 527^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=577.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 665858.

It is not an unprimeable number, because it can be changed into a prime (665857) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 866 + ... + 1442.

2⁶⁶⁵⁸⁵⁸ is an apocalyptic number.

665858 is a deficient number, since it is larger than the sum of its proper divisors (334663).

665858 is an frugal number, since it uses more digits than its factorization.

665858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1156 (or 579 counting only the distinct ones).

The product of its digits is 57600, while the sum is 38.

The square root of 665858 is about 816.0012254893. The cubic root of 665858 is about 87.3227104121.

The spelling of 665858 in words is "six hundred sixty-five thousand, eight hundred fifty-eight".