8666645221 has 4 divisors (see below), whose sum is σ = 9333310252. Its totient is φ = 7999980192.

The previous prime is 8666645213. The next prime is 8666645303. The reversal of 8666645221 is 1225466668.

8666645221 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5551889121 + 3114756100 = 74511^2 + 55810^2 .

It is a cyclic number.

It is not a de Polignac number, because 8666645221 - 2³ = 8666645213 is a prime.

It is a super-3 number, since 3×8666645221³ (a number of 31 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8666645201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 333332496 + ... + 333332521.

It is an arithmetic number, because the mean of its divisors is an integer number (2333327563).

Almost surely, 2^8666645221 is an apocalyptic number.

It is an amenable number.

8666645221 is a deficient number, since it is larger than the sum of its proper divisors (666665031).

8666645221 is a wasteful number, since it uses less digits than its factorization.

8666645221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 666665030.

The product of its digits is 829440, while the sum is 46.

The square root of 8666645221 is about 93094.8184433484. The cubic root of 8666645221 is about 2054.0783549746.

The spelling of 8666645221 in words is "eight billion, six hundred sixty-six million, six hundred forty-five thousand, two hundred twenty-one".