999999689 has 4 divisors (see below), whose sum is σ = 1076922756. Its totient is φ = 923076624.

The previous prime is 999999677. The next prime is 999999733. The reversal of 999999689 is 986999999.

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 329604025 + 670395664 = 18155^2 + 25892^2 .

It is a cyclic number.

It is not a de Polignac number, because 999999689 - 2⁸ = 999999433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (999996689) 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, 38461514 + ... + 38461539.

It is an arithmetic number, because the mean of its divisors is an integer number (269230689).

Almost surely, 2^999999689 is an apocalyptic number.

It is an amenable number.

999999689 is a deficient number, since it is larger than the sum of its proper divisors (76923067).

999999689 is a wasteful number, since it uses less digits than its factorization.

999999689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76923066.

The product of its digits is 229582512, while the sum is 77.

The square root of 999999689 is about 31622.7716843416. The cubic root of 999999689 is about 999.9998963333. Note that the first 3 decimals are identical.

The spelling of 999999689 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, six hundred eighty-nine".