10000009991 has 4 divisors (see below), whose sum is σ = 10012717272. Its totient is φ = 9987302712.

The previous prime is 10000009973. The next prime is 10000009993. The reversal of 10000009991 is 19990000001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19990000001 = 17 ⋅1175882353.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-10000009991 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 (10000009993) 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, 6352460 + ... + 6354033.

It is an arithmetic number, because the mean of its divisors is an integer number (2503179318).

Almost surely, 2^10000009991 is an apocalyptic number.

10000009991 is a deficient number, since it is larger than the sum of its proper divisors (12707281).

10000009991 is an equidigital number, since it uses as much as digits as its factorization.

10000009991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12707280.

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

Adding to 10000009991 its reverse (19990000001), we get a palindrome (29990009992).

The spelling of 10000009991 in words is "ten billion, nine thousand, nine hundred ninety-one".