6561161616605 has 16 divisors (see below), whose sum is σ = 8020343770560. Its totient is φ = 5151262795008.

The previous prime is 6561161616517. The next prime is 6561161616643. The reversal of 6561161616605 is 5066161611656.

It is a cyclic number.

It is not a de Polignac number, because 6561161616605 - 2²⁶ = 6561094507741 is a prime.

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, 18578207 + ... + 18928076.

It is an arithmetic number, because the mean of its divisors is an integer number (501271485660).

Almost surely, 2^{6561161616605} is an apocalyptic number.

It is an amenable number.

6561161616605 is a deficient number, since it is larger than the sum of its proper divisors (1459182153955).

6561161616605 is a wasteful number, since it uses less digits than its factorization.

6561161616605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37506940.

The product of its (nonzero) digits is 1166400, while the sum is 50.

The spelling of 6561161616605 in words is "six trillion, five hundred sixty-one billion, one hundred sixty-one million, six hundred sixteen thousand, six hundred five".