866518521 has 16 divisors (see below), whose sum is σ = 1303853760. Its totient is φ = 507053120.

The previous prime is 866518517. The next prime is 866518529. The reversal of 866518521 is 125815668.

It is a cyclic number.

It is not a de Polignac number, because 866518521 - 2² = 866518517 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (866518529) 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, 451770 + ... + 453683.

It is an arithmetic number, because the mean of its divisors is an integer number (81490860).

Almost surely, 2^866518521 is an apocalyptic number.

It is an amenable number.

866518521 is a deficient number, since it is larger than the sum of its proper divisors (437335239).

866518521 is a wasteful number, since it uses less digits than its factorization.

866518521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 905496.

The product of its digits is 115200, while the sum is 42.

The square root of 866518521 is about 29436.6866511841. The cubic root of 866518521 is about 953.3651739111.

The spelling of 866518521 in words is "eight hundred sixty-six million, five hundred eighteen thousand, five hundred twenty-one".