9991331 has 16 divisors (see below), whose sum is σ = 12085248. Its totient is φ = 8078400.

The previous prime is 9991313. The next prime is 9991337. The reversal of 9991331 is 1331999.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 9991331 - 2¹⁰ = 9990307 is a prime.

It is a super-2 number, since 2×9991331² = 199653390303122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 9991291 and 9991300.

It is not an unprimeable number, because it can be changed into a prime (9991337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8336 + ... + 9458.

It is an arithmetic number, because the mean of its divisors is an integer number (755328).

Almost surely, 2^9991331 is an apocalyptic number.

9991331 is a deficient number, since it is larger than the sum of its proper divisors (2093917).

9991331 is a wasteful number, since it uses less digits than its factorization.

9991331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1202.

The product of its digits is 6561, while the sum is 35.

The square root of 9991331 is about 3160.9066737251. The cubic root of 9991331 is about 215.3811950235.

The spelling of 9991331 in words is "nine million, nine hundred ninety-one thousand, three hundred thirty-one".