865220191 has 16 divisors (see below), whose sum is σ = 992995200. Its totient is φ = 746552800.

The previous prime is 865220189. The next prime is 865220197. The reversal of 865220191 is 191022568.

It is not a de Polignac number, because 865220191 - 2¹ = 865220189 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 (865220197) 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 15 ways as a sum of consecutive naturals, for example, 4165 + ... + 41806.

It is an arithmetic number, because the mean of its divisors is an integer number (62062200).

Almost surely, 2^865220191 is an apocalyptic number.

865220191 is a deficient number, since it is larger than the sum of its proper divisors (127775009).

865220191 is a wasteful number, since it uses less digits than its factorization.

865220191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46070.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 865220191 is about 29414.6254608146. The cubic root of 865220191 is about 952.8887842771. Note that the first 3 decimals are identical.

The spelling of 865220191 in words is "eight hundred sixty-five million, two hundred twenty thousand, one hundred ninety-one".