9821006991 has 12 divisors (see below), whose sum is σ = 14186874000. Its totient is φ = 6546888000.

The previous prime is 9821006971. The next prime is 9821006999. The reversal of 9821006991 is 1996001289.

It is not a de Polignac number, because 9821006991 - 2⁵ = 9821006959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9821006999) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 150135 + ... + 205383.

It is an arithmetic number, because the mean of its divisors is an integer number (1182239500).

Almost surely, 2^9821006991 is an apocalyptic number.

9821006991 is a deficient number, since it is larger than the sum of its proper divisors (4365867009).

9821006991 is a wasteful number, since it uses less digits than its factorization.

9821006991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75006 (or 75003 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 45.

The square root of 9821006991 is about 99100.9938951169. The cubic root of 9821006991 is about 2141.5029322848.

The spelling of 9821006991 in words is "nine billion, eight hundred twenty-one million, six thousand, nine hundred ninety-one".