999689 has 4 divisors (see below), whose sum is σ = 1007124. Its totient is φ = 992256.

The previous prime is 999683. The next prime is 999721. The reversal of 999689 is 986999.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 462400 + 537289 = 680^2 + 733^2 .

It is a cyclic number.

It is not a de Polignac number, because 999689 - 2⁸ = 999433 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 999689.

It is not an unprimeable number, because it can be changed into a prime (999683) 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, 3512 + ... + 3785.

It is an arithmetic number, because the mean of its divisors is an integer number (251781).

2⁹⁹⁹⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

999689 is a deficient number, since it is larger than the sum of its proper divisors (7435).

999689 is a wasteful number, since it uses less digits than its factorization.

999689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7434.

The product of its digits is 314928, while the sum is 50.

The square root of 999689 is about 999.8444879080. The cubic root of 999689 is about 99.9896322585.

The spelling of 999689 in words is "nine hundred ninety-nine thousand, six hundred eighty-nine".