864811521 has 12 divisors (see below), whose sum is σ = 1427625472. Its totient is φ = 494177976.

The previous prime is 864811517. The next prime is 864811537. The reversal of 864811521 is 125118468.

864811521 is a `hidden beast` number, since 8 + 648 + 1 + 1 + 5 + 2 + 1 = 666.

864811521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 864811521 - 2² = 864811517 is a prime.

It is not an unprimeable number, because it can be changed into a prime (864811021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6863521 + ... + 6863646.

Almost surely, 2^864811521 is an apocalyptic number.

It is an amenable number.

864811521 is a deficient number, since it is larger than the sum of its proper divisors (562813951).

864811521 is a wasteful number, since it uses less digits than its factorization.

864811521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13727180 (or 13727177 counting only the distinct ones).

The product of its digits is 15360, while the sum is 36.

The square root of 864811521 is about 29407.6779260111. The cubic root of 864811521 is about 952.7387344629.

Adding to 864811521 its reverse (125118468), we get a palindrome (989929989).

The spelling of 864811521 in words is "eight hundred sixty-four million, eight hundred eleven thousand, five hundred twenty-one".