6640015221 has 24 divisors (see below), whose sum is σ = 10969455744. Its totient is φ = 3791469600.

The previous prime is 6640015183. The next prime is 6640015241. The reversal of 6640015221 is 1225100466.

6640015221 is a `hidden beast` number, since 6 + 640 + 0 + 15 + 2 + 2 + 1 = 666.

It is not a de Polignac number, because 6640015221 - 2³⁰ = 5566273397 is a prime.

It is a super-2 number, since 2×6640015221² = 88179604270223357682, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640015241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 47571 + ... + 124671.

It is an arithmetic number, because the mean of its divisors is an integer number (457060656).

Almost surely, 2^6640015221 is an apocalyptic number.

It is an amenable number.

6640015221 is a deficient number, since it is larger than the sum of its proper divisors (4329440523).

6640015221 is a wasteful number, since it uses less digits than its factorization.

6640015221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78481 (or 78478 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 6640015221 is about 81486.2885459879. The cubic root of 6640015221 is about 1879.5607111728.

Adding to 6640015221 its reverse (1225100466), we get a palindrome (7865115687).

The spelling of 6640015221 in words is "six billion, six hundred forty million, fifteen thousand, two hundred twenty-one".