999689665 has 16 divisors (see below), whose sum is σ = 1292569488. Its totient is φ = 737853696.

The previous prime is 999689629. The next prime is 999689681. The reversal of 999689665 is 566986999.

999689665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 3908529 + 995781136 = 1977^2 + 31556^2 .

It is a cyclic number.

It is not a de Polignac number, because 999689665 - 2²⁹ = 462818753 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 999689665.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 226419 + ... + 230791.

It is an arithmetic number, because the mean of its divisors is an integer number (80785593).

Almost surely, 2^999689665 is an apocalyptic number.

It is an amenable number.

999689665 is a deficient number, since it is larger than the sum of its proper divisors (292879823).

999689665 is a wasteful number, since it uses less digits than its factorization.

999689665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7908.

The product of its digits is 56687040, while the sum is 67.

The square root of 999689665 is about 31617.8693937463. The cubic root of 999689665 is about 999.8965442973.

The spelling of 999689665 in words is "nine hundred ninety-nine million, six hundred eighty-nine thousand, six hundred sixty-five".