811991845 has 8 divisors (see below), whose sum is σ = 1113588864. Its totient is φ = 556794384.

The previous prime is 811991819. The next prime is 811991849. The reversal of 811991845 is 548199118.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 811991845 - 2¹¹ = 811989797 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 811991795 and 811991804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (811991849) 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 7 ways as a sum of consecutive naturals, for example, 11599849 + ... + 11599918.

It is an arithmetic number, because the mean of its divisors is an integer number (139198608).

Almost surely, 2^811991845 is an apocalyptic number.

It is an amenable number.

811991845 is a deficient number, since it is larger than the sum of its proper divisors (301597019).

811991845 is a wasteful number, since it uses less digits than its factorization.

811991845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23199779.

The product of its digits is 103680, while the sum is 46.

The square root of 811991845 is about 28495.4706049926. The cubic root of 811991845 is about 932.9332158961.

The spelling of 811991845 in words is "eight hundred eleven million, nine hundred ninety-one thousand, eight hundred forty-five".