10009991 has 8 divisors (see below), whose sum is σ = 11060064. Its totient is φ = 9011200.

The previous prime is 10009981. The next prime is 10010023. The reversal of 10009991 is 19990001.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 10009991 - 2¹⁰ = 10008967 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10009921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12410 + ... + 13191.

It is an arithmetic number, because the mean of its divisors is an integer number (1382508).

Almost surely, 2^10009991 is an apocalyptic number.

10009991 is a deficient number, since it is larger than the sum of its proper divisors (1050073).

10009991 is a wasteful number, since it uses less digits than its factorization.

10009991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25641.

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

The square root of 10009991 is about 3163.8569815970. The cubic root of 10009991 is about 215.5151949780.

Adding to 10009991 its reverse (19990001), we get a palindrome (29999992).

The spelling of 10009991 in words is "ten million, nine thousand, nine hundred ninety-one".