865949992821 has 24 divisors (see below), whose sum is σ = 1252988162816. Its totient is φ = 576298644480.

The previous prime is 865949992819. The next prime is 865949992829. The reversal of 865949992821 is 128299949568.

865949992821 is a `hidden beast` number, since 8 + 6 + 59 + 499 + 9 + 2 + 82 + 1 = 666.

It is not a de Polignac number, because 865949992821 - 2¹ = 865949992819 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 865949992821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (865949992829) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12115836 + ... + 12187098.

Almost surely, 2^865949992821 is an apocalyptic number.

It is an amenable number.

865949992821 is a deficient number, since it is larger than the sum of its proper divisors (387038169995).

865949992821 is a wasteful number, since it uses less digits than its factorization.

865949992821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73593 (or 73590 counting only the distinct ones).

The product of its digits is 201553920, while the sum is 72.

The spelling of 865949992821 in words is "eight hundred sixty-five billion, nine hundred forty-nine million, nine hundred ninety-two thousand, eight hundred twenty-one".