6561665560 has 16 divisors (see below), whose sum is σ = 14763747600. Its totient is φ = 2624666208.

The previous prime is 6561665549. The next prime is 6561665567. The reversal of 6561665560 is 655661656.

It is a super-2 number, since 2×6561665560² = 86110909842580227200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 6561665560.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561665567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82020780 + ... + 82020859.

It is an arithmetic number, because the mean of its divisors is an integer number (922734225).

Almost surely, 2^6561665560 is an apocalyptic number.

It is an amenable number.

6561665560 is an abundant number, since it is smaller than the sum of its proper divisors (8202082040).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6561665560 is a wasteful number, since it uses less digits than its factorization.

6561665560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164041650 (or 164041646 counting only the distinct ones).

The product of its (nonzero) digits is 972000, while the sum is 46.

The square root of 6561665560 is about 81004.1082908762. The cubic root of 6561665560 is about 1872.1387408738.

The spelling of 6561665560 in words is "six billion, five hundred sixty-one million, six hundred sixty-five thousand, five hundred sixty".