999959999 has 4 divisors (see below), whose sum is σ = 1000430064. Its totient is φ = 999489936.

The previous prime is 999959993. The next prime is 999960011.

It is a happy number.

999959999 is nontrivially palindromic in base 10.

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 999959999 - 2²⁰ = 998911423 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999959993) 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, 231827 + ... + 236100.

It is an arithmetic number, because the mean of its divisors is an integer number (250107516).

Almost surely, 2^999959999 is an apocalyptic number.

999959999 is a deficient number, since it is larger than the sum of its proper divisors (470065).

999959999 is a wasteful number, since it uses less digits than its factorization.

999959999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 470064.

The product of its digits is 215233605, while the sum is 77.

The square root of 999959999 is about 31622.1441240154. The cubic root of 999959999 is about 999.9866661555.

The spelling of 999959999 in words is "nine hundred ninety-nine million, nine hundred fifty-nine thousand, nine hundred ninety-nine".