865928885809 has 27 divisors (see below), whose sum is σ = 958666841643. Its totient is φ = 781798519632.

The previous prime is 865928885791. The next prime is 865928885819. The reversal of 865928885809 is 908588829568.

The square root of 865928885809 is 930553.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 128095989025 + 737832896784 = 357905^2 + 858972^2 .

It is not a de Polignac number, because 865928885809 - 2²³ = 865920497201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (865928885819) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 568567122 + ... + 568568644.

Almost surely, 2^865928885809 is an apocalyptic number.

865928885809 is the 930553-rd square number.

865928885809 is the 465277-th centered octagonal number.

It is an amenable number.

865928885809 is a deficient number, since it is larger than the sum of its proper divisors (92737955834).

865928885809 is an frugal number, since it uses more digits than its factorization.

865928885809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3166 (or 1583 counting only the distinct ones).

The product of its (nonzero) digits is 796262400, while the sum is 76.

The spelling of 865928885809 in words is "eight hundred sixty-five billion, nine hundred twenty-eight million, eight hundred eighty-five thousand, eight hundred nine".