665785 has 4 divisors (see below), whose sum is σ = 798948. Its totient is φ = 532624.

The previous prime is 665783. The next prime is 665789. The reversal of 665785 is 587566.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 94249 + 571536 = 307^2 + 756^2 .

It is a cyclic number.

It is not a de Polignac number, because 665785 - 2¹ = 665783 is a prime.

It is a Duffinian number.

665785 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (665783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66574 + ... + 66583.

It is an arithmetic number, because the mean of its divisors is an integer number (199737).

2⁶⁶⁵⁷⁸⁵ is an apocalyptic number.

It is an amenable number.

665785 is a deficient number, since it is larger than the sum of its proper divisors (133163).

665785 is a wasteful number, since it uses less digits than its factorization.

665785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133162.

The product of its digits is 50400, while the sum is 37.

The square root of 665785 is about 815.9564939382. The cubic root of 665785 is about 87.3195191457.

The spelling of 665785 in words is "six hundred sixty-five thousand, seven hundred eighty-five".