665365 has 4 divisors (see below), whose sum is σ = 798444. Its totient is φ = 532288.

The previous prime is 665359. The next prime is 665369. The reversal of 665365 is 563566.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 563566 = 2 ⋅281783.

It can be written as a sum of positive squares in 2 ways, for example, as 376996 + 288369 = 614^2 + 537^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665365 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665369) 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, 66532 + ... + 66541.

It is an arithmetic number, because the mean of its divisors is an integer number (199611).

2⁶⁶⁵³⁶⁵ is an apocalyptic number.

It is an amenable number.

665365 is a deficient number, since it is larger than the sum of its proper divisors (133079).

665365 is a wasteful number, since it uses less digits than its factorization.

665365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133078.

The product of its digits is 16200, while the sum is 31.

The square root of 665365 is about 815.6990866735. The cubic root of 665365 is about 87.3011539014.

The spelling of 665365 in words is "six hundred sixty-five thousand, three hundred sixty-five".