999799999 has 4 divisors (see below), whose sum is σ = 1090690920. Its totient is φ = 908909080.

The previous prime is 999799987. The next prime is 999800059. The reversal of 999799999 is 999997999.

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

It is a cyclic number.

It is not a de Polignac number, because 999799999 - 2²¹ = 997702847 is a prime.

999799999 is a modest number, since divided by 99999 gives 9997 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999799979) 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, 45445444 + ... + 45445465.

It is an arithmetic number, because the mean of its divisors is an integer number (272672730).

Almost surely, 2^999799999 is an apocalyptic number.

999799999 is a deficient number, since it is larger than the sum of its proper divisors (90890921).

999799999 is a wasteful number, since it uses less digits than its factorization.

999799999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90890920.

The product of its digits is 301327047, while the sum is 79.

The square root of 999799999 is about 31619.6141500810. The cubic root of 999799999 is about 999.9333285550.

The spelling of 999799999 in words is "nine hundred ninety-nine million, seven hundred ninety-nine thousand, nine hundred ninety-nine".