812721865 has 8 divisors (see below), whose sum is σ = 1026596160. Its totient is φ = 615957552.

The previous prime is 812721863. The next prime is 812721869. The reversal of 812721865 is 568127218.

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 812721865 - 2¹ = 812721863 is a prime.

It is not an unprimeable number, because it can be changed into a prime (812721863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4277389 + ... + 4277578.

It is an arithmetic number, because the mean of its divisors is an integer number (128324520).

Almost surely, 2^812721865 is an apocalyptic number.

It is an amenable number.

812721865 is a deficient number, since it is larger than the sum of its proper divisors (213874295).

812721865 is a wasteful number, since it uses less digits than its factorization.

812721865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8554991.

The product of its digits is 53760, while the sum is 40.

The square root of 812721865 is about 28508.2771313876. The cubic root of 812721865 is about 933.2127162015.

It can be divided in two parts, 8127 and 21865, that added together give a palindrome (29992).

The spelling of 812721865 in words is "eight hundred twelve million, seven hundred twenty-one thousand, eight hundred sixty-five".