999909 has 12 divisors (see below), whose sum is σ = 1453452. Its totient is φ = 662400.

The previous prime is 999907. The next prime is 999917. The reversal of 999909 is 909999.

It can be written as a sum of positive squares in 2 ways, for example, as 540225 + 459684 = 735^2 + 678^2 .

It is not a de Polignac number, because 999909 - 2¹ = 999907 is a prime.

It is a Curzon number.

999909 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1939 + ... + 2399.

It is an arithmetic number, because the mean of its divisors is an integer number (121121).

2⁹⁹⁹⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

999909 is a deficient number, since it is larger than the sum of its proper divisors (453543).

999909 is a wasteful number, since it uses less digits than its factorization.

999909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 708 (or 705 counting only the distinct ones).

The product of its (nonzero) digits is 59049, while the sum is 45.

The square root of 999909 is about 999.9544989648. The cubic root of 999909 is about 99.9969665747.

It can be divided in two parts, 99990 and 9, that added together give a palindrome (99999).

The spelling of 999909 in words is "nine hundred ninety-nine thousand, nine hundred nine".