8331991 has 4 divisors (see below), whose sum is σ = 8353800. Its totient is φ = 8310184.

The previous prime is 8331977. The next prime is 8331997. The reversal of 8331991 is 1991338.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1991338 = 2 ⋅995669.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8331991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8331997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10321 + ... + 11098.

It is an arithmetic number, because the mean of its divisors is an integer number (2088450).

Almost surely, 2^8331991 is an apocalyptic number.

8331991 is a deficient number, since it is larger than the sum of its proper divisors (21809).

8331991 is a wasteful number, since it uses less digits than its factorization.

8331991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21808.

The product of its digits is 5832, while the sum is 34.

The square root of 8331991 is about 2886.5188376312. The cubic root of 8331991 is about 202.7291801446.

The spelling of 8331991 in words is "eight million, three hundred thirty-one thousand, nine hundred ninety-one".