809665 has 8 divisors (see below), whose sum is σ = 983808. Its totient is φ = 639600.

The previous prime is 809629. The next prime is 809701. The reversal of 809665 is 566908.

It is an interprime number because it is at equal distance from previous prime (809629) and next prime (809701).

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

It is not a de Polignac number, because 809665 - 2¹⁷ = 678593 is a prime.

It is an Ulam number.

It is a Duffinian number.

809665 is a lucky number.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 809665.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 561 + ... + 1390.

It is an arithmetic number, because the mean of its divisors is an integer number (122976).

2⁸⁰⁹⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

809665 is a deficient number, since it is larger than the sum of its proper divisors (174143).

809665 is a wasteful number, since it uses less digits than its factorization.

809665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2039.

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 809665 is about 899.8138696419. The cubic root of 809665 is about 93.2041225067.

The spelling of 809665 in words is "eight hundred nine thousand, six hundred sixty-five".