9991331320121 has 4 divisors (see below), whose sum is σ = 9991382112000. Its totient is φ = 9991280528244.

The previous prime is 9991331320109. The next prime is 9991331320129. The reversal of 9991331320121 is 1210231331999.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 9991331320121 - 2⁶ = 9991331320057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9991331320129) 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 3 ways as a sum of consecutive naturals, for example, 25099721 + ... + 25494678.

It is an arithmetic number, because the mean of its divisors is an integer number (2497845528000).

Almost surely, 2^{9991331320121} is an apocalyptic number.

It is an amenable number.

9991331320121 is a deficient number, since it is larger than the sum of its proper divisors (50791879).

9991331320121 is a wasteful number, since it uses less digits than its factorization.

9991331320121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50791878.

The product of its (nonzero) digits is 78732, while the sum is 44.

The spelling of 9991331320121 in words is "nine trillion, nine hundred ninety-one billion, three hundred thirty-one million, three hundred twenty thousand, one hundred twenty-one".