991000010009 has 4 divisors (see below), whose sum is σ = 999769921716. Its totient is φ = 982230098304.

The previous prime is 991000010003. The next prime is 991000010027. The reversal of 991000010009 is 900010000199.

991000010009 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 269397331225 + 721602678784 = 519035^2 + 849472^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991000010009 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (991000010003) 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, 4384955684 + ... + 4384955909.

It is an arithmetic number, because the mean of its divisors is an integer number (249942480429).

Almost surely, 2^991000010009 is an apocalyptic number.

It is an amenable number.

991000010009 is a deficient number, since it is larger than the sum of its proper divisors (8769911707).

991000010009 is a wasteful number, since it uses less digits than its factorization.

991000010009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8769911706.

The product of its (nonzero) digits is 729, while the sum is 29.

The spelling of 991000010009 in words is "nine hundred ninety-one billion, ten thousand, nine".