9491801991 has 16 divisors (see below), whose sum is σ = 14930270208. Its totient is φ = 5248922400.

The previous prime is 9491801939. The next prime is 9491802017. The reversal of 9491801991 is 1991081949.

9491801991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 9491801991 - 2⁶ = 9491801927 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9491801791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7289520 + ... + 7290821.

It is an arithmetic number, because the mean of its divisors is an integer number (933141888).

Almost surely, 2^9491801991 is an apocalyptic number.

9491801991 is a deficient number, since it is larger than the sum of its proper divisors (5438468217).

9491801991 is a wasteful number, since it uses less digits than its factorization.

9491801991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14580382.

The product of its (nonzero) digits is 209952, while the sum is 51.

The square root of 9491801991 is about 97425.8794725508. The cubic root of 9491801991 is about 2117.3024006647.

The spelling of 9491801991 in words is "nine billion, four hundred ninety-one million, eight hundred one thousand, nine hundred ninety-one".