6561917385 has 16 divisors (see below), whose sum is σ = 10500319680. Its totient is φ = 3499272000.

The previous prime is 6561917317. The next prime is 6561917389. The reversal of 6561917385 is 5837191656.

It is not a de Polignac number, because 6561917385 - 2¹¹ = 6561915337 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6561917389) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 136686 + ... + 178344.

It is an arithmetic number, because the mean of its divisors is an integer number (656269980).

Almost surely, 2^6561917385 is an apocalyptic number.

It is an amenable number.

6561917385 is a deficient number, since it is larger than the sum of its proper divisors (3938402295).

6561917385 is a wasteful number, since it uses less digits than its factorization.

6561917385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52168.

The product of its digits is 1360800, while the sum is 51.

The square root of 6561917385 is about 81005.6626724330. The cubic root of 6561917385 is about 1872.1626903473.

The spelling of 6561917385 in words is "six billion, five hundred sixty-one million, nine hundred seventeen thousand, three hundred eighty-five".