665800 has 24 divisors (see below), whose sum is σ = 1548450. Its totient is φ = 266240.

The previous prime is 665789. The next prime is 665801. The reversal of 665800 is 8566.

It can be written as a sum of positive squares in 3 ways, for example, as 459684 + 206116 = 678^2 + 454^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665801) by changing a digit.

665800 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1465 + ... + 1864.

2⁶⁶⁵⁸⁰⁰ is an apocalyptic number.

It is an amenable number.

665800 is an abundant number, since it is smaller than the sum of its proper divisors (882650).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

665800 is a wasteful number, since it uses less digits than its factorization.

665800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3345 (or 3336 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 665800 is about 815.9656855530. The cubic root of 665800 is about 87.3201749044.

The spelling of 665800 in words is "six hundred sixty-five thousand, eight hundred".