8205991 has 4 divisors (see below), whose sum is σ = 8396872. Its totient is φ = 8015112.

The previous prime is 8205983. The next prime is 8206013. The reversal of 8205991 is 1995028.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 8205991 - 2³ = 8205983 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 (8205931) 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, 95376 + ... + 95461.

It is an arithmetic number, because the mean of its divisors is an integer number (2099218).

Almost surely, 2^8205991 is an apocalyptic number.

8205991 is a deficient number, since it is larger than the sum of its proper divisors (190881).

8205991 is a wasteful number, since it uses less digits than its factorization.

8205991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190880.

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 8205991 is about 2864.6100956326. The cubic root of 8205991 is about 201.7020654418.

The spelling of 8205991 in words is "eight million, two hundred five thousand, nine hundred ninety-one".