6561205505605 has 16 divisors (see below), whose sum is σ = 7941779426304. Its totient is φ = 5203584070720.

The previous prime is 6561205505599. The next prime is 6561205505633. The reversal of 6561205505605 is 5065055021656.

It is not a de Polignac number, because 6561205505605 - 2⁹ = 6561205505093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10629541 + ... + 11229850.

It is an arithmetic number, because the mean of its divisors is an integer number (496361214144).

Almost surely, 2^{6561205505605} is an apocalyptic number.

It is an amenable number.

6561205505605 is a deficient number, since it is larger than the sum of its proper divisors (1380573920699).

6561205505605 is a wasteful number, since it uses less digits than its factorization.

6561205505605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21859916.

The product of its (nonzero) digits is 1350000, while the sum is 46.

The spelling of 6561205505605 in words is "six trillion, five hundred sixty-one billion, two hundred five million, five hundred five thousand, six hundred five".