9009007991 has 16 divisors (see below), whose sum is σ = 9405247488. Its totient is φ = 8619652800.

The previous prime is 9009007981. The next prime is 9009007993. The reversal of 9009007991 is 1997009009.

It is a cyclic number.

It is not a de Polignac number, because 9009007991 - 2¹⁰ = 9009006967 is a prime.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9009007993) 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 15 ways as a sum of consecutive naturals, for example, 2319371 + ... + 2323251.

It is an arithmetic number, because the mean of its divisors is an integer number (587827968).

Almost surely, 2^9009007991 is an apocalyptic number.

9009007991 is a deficient number, since it is larger than the sum of its proper divisors (396239497).

9009007991 is a wasteful number, since it uses less digits than its factorization.

9009007991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4742.

The product of its (nonzero) digits is 45927, while the sum is 44.

The square root of 9009007991 is about 94915.7942125545. The cubic root of 9009007991 is about 2080.7775685517. Note that the first 3 decimals are identical.

The spelling of 9009007991 in words is "nine billion, nine million, seven thousand, nine hundred ninety-one".