864505809 has 12 divisors (see below), whose sum is σ = 1249612416. Its totient is φ = 575930232.

The previous prime is 864505799. The next prime is 864505823. The reversal of 864505809 is 908505468.

864505809 is a `hidden beast` number, since 8 + 64 + 5 + 0 + 580 + 9 = 666.

It is not a de Polignac number, because 864505809 - 2⁹ = 864505297 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (864501809) 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 11 ways as a sum of consecutive naturals, for example, 20169 + ... + 46214.

It is an arithmetic number, because the mean of its divisors is an integer number (104134368).

Almost surely, 2^864505809 is an apocalyptic number.

It is an amenable number.

864505809 is a deficient number, since it is larger than the sum of its proper divisors (385106607).

864505809 is a wasteful number, since it uses less digits than its factorization.

864505809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67836 (or 67833 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

The square root of 864505809 is about 29402.4796403297. The cubic root of 864505809 is about 952.6264564368.

The spelling of 864505809 in words is "eight hundred sixty-four million, five hundred five thousand, eight hundred nine".