6561556555100 has 18 divisors (see below), whose sum is σ = 14238577724784. Its totient is φ = 2624622622000.

The previous prime is 6561556555091. The next prime is 6561556555189. The reversal of 6561556555100 is 15556551656.

It is a Harshad number since it is a multiple of its sum of digits (50).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32807782676 + ... + 32807782875.

Almost surely, 2^{6561556555100} is an apocalyptic number.

It is an amenable number.

6561556555100 is an abundant number, since it is smaller than the sum of its proper divisors (7677021169684).

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

6561556555100 is a wasteful number, since it uses less digits than its factorization.

6561556555100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65615565565 (or 65615565558 counting only the distinct ones).

The product of its (nonzero) digits is 3375000, while the sum is 50.

The spelling of 6561556555100 in words is "six trillion, five hundred sixty-one billion, five hundred fifty-six million, five hundred fifty-five thousand, one hundred".