819791865 has 24 divisors (see below), whose sum is σ = 1469973960. Its totient is φ = 422145024.

The previous prime is 819791849. The next prime is 819791887. The reversal of 819791865 is 568197918.

It can be written as a sum of positive squares in 4 ways, for example, as 441 + 819791424 = 21^2 + 28632^2 .

It is not a de Polignac number, because 819791865 - 2⁴ = 819791849 is a prime.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 312792 + ... + 315401.

It is an arithmetic number, because the mean of its divisors is an integer number (61248915).

Almost surely, 2^819791865 is an apocalyptic number.

It is an amenable number.

819791865 is a deficient number, since it is larger than the sum of its proper divisors (650182095).

819791865 is a wasteful number, since it uses less digits than its factorization.

819791865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 628233 (or 628230 counting only the distinct ones).

The product of its digits is 1088640, while the sum is 54.

The square root of 819791865 is about 28632.0077011725. The cubic root of 819791865 is about 935.9109636160.

The spelling of 819791865 in words is "eight hundred nineteen million, seven hundred ninety-one thousand, eight hundred sixty-five".