999666999 has 12 divisors (see below), whose sum is σ = 1482989976. Its totient is φ = 648432432.

The previous prime is 999666979. The next prime is 999667021.

999666999 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 999666999 - 2¹¹ = 999664951 is a prime.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999666949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1500669 + ... + 1501334.

It is an arithmetic number, because the mean of its divisors is an integer number (123582498).

Almost surely, 2^999666999 is an apocalyptic number.

999666999 is a deficient number, since it is larger than the sum of its proper divisors (483322977).

999666999 is a wasteful number, since it uses less digits than its factorization.

999666999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3002046 (or 3002043 counting only the distinct ones).

The product of its digits is 114791256, while the sum is 72.

The square root of 999666999 is about 31617.5109551653. The cubic root of 999666999 is about 999.8889873433. Note that the first 3 decimals are identical.

The spelling of 999666999 in words is "nine hundred ninety-nine million, six hundred sixty-six thousand, nine hundred ninety-nine".