6515620221 has 24 divisors (see below), whose sum is σ = 9691622752. Its totient is φ = 3889908000.

The previous prime is 6515620213. The next prime is 6515620249. The reversal of 6515620221 is 1220265156.

It is not a de Polignac number, because 6515620221 - 2³ = 6515620213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6515620121) 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, 109630 + ... + 158271.

Almost surely, 2^6515620221 is an apocalyptic number.

It is an amenable number.

6515620221 is a deficient number, since it is larger than the sum of its proper divisors (3176002531).

6515620221 is a wasteful number, since it uses less digits than its factorization.

6515620221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267993 (or 267982 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 6515620221 is about 80719.3918522681. The cubic root of 6515620221 is about 1867.7493222247.

Adding to 6515620221 its reverse (1220265156), we get a palindrome (7735885377).

The spelling of 6515620221 in words is "six billion, five hundred fifteen million, six hundred twenty thousand, two hundred twenty-one".