851221064565 has 16 divisors (see below), whose sum is σ = 1513281892800. Its totient is φ = 453984567696.

The previous prime is 851221064563. The next prime is 851221064579. The reversal of 851221064565 is 565460122158.

851221064565 is a `hidden beast` number, since 8 + 5 + 1 + 2 + 21 + 0 + 64 + 565 = 666.

It is not a de Polignac number, because 851221064565 - 2¹ = 851221064563 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 851221064565.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (851221064563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3152670475 + ... + 3152670744.

It is an arithmetic number, because the mean of its divisors is an integer number (94580118300).

Almost surely, 2^851221064565 is an apocalyptic number.

It is an amenable number.

851221064565 is a deficient number, since it is larger than the sum of its proper divisors (662060828235).

851221064565 is a wasteful number, since it uses less digits than its factorization.

851221064565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6305341233 (or 6305341227 counting only the distinct ones).

The product of its (nonzero) digits is 576000, while the sum is 45.

The spelling of 851221064565 in words is "eight hundred fifty-one billion, two hundred twenty-one million, sixty-four thousand, five hundred sixty-five".