656665 has 8 divisors (see below), whose sum is σ = 801288. Its totient is φ = 516480.

The previous prime is 656657. The next prime is 656671. The reversal of 656665 is 566656.

It can be written as a sum of positive squares in 4 ways, for example, as 35721 + 620944 = 189^2 + 788^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 656665 - 2³ = 656657 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 656665.

It is an unprimeable 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 7 ways as a sum of consecutive naturals, for example, 772 + ... + 1381.

It is an arithmetic number, because the mean of its divisors is an integer number (100161).

2⁶⁵⁶⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

656665 is a deficient number, since it is larger than the sum of its proper divisors (144623).

656665 is a wasteful number, since it uses less digits than its factorization.

656665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2219.

The product of its digits is 32400, while the sum is 34.

The square root of 656665 is about 810.3486903796. The cubic root of 656665 is about 86.9189803708.

Subtracting from 656665 its reverse (566656), we obtain a palindrome (90009).

The spelling of 656665 in words is "six hundred fifty-six thousand, six hundred sixty-five".