865665 has 12 divisors (see below), whose sum is σ = 1500564. Its totient is φ = 461664.

The previous prime is 865661. The next prime is 865681. The reversal of 865665 is 566568.

It can be written as a sum of positive squares in 2 ways, for example, as 199809 + 665856 = 447^2 + 816^2 .

It is not a de Polignac number, because 865665 - 2² = 865661 is a prime.

865665 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (865661) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9574 + ... + 9663.

It is an arithmetic number, because the mean of its divisors is an integer number (125047).

2⁸⁶⁵⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

865665 is a deficient number, since it is larger than the sum of its proper divisors (634899).

865665 is a wasteful number, since it uses less digits than its factorization.

865665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19248 (or 19245 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 865665 is about 930.4111994167. The cubic root of 865665 is about 95.3052049420.

The spelling of 865665 in words is "eight hundred sixty-five thousand, six hundred sixty-five".