6565511561 has 4 divisors (see below), whose sum is σ = 7503441792. Its totient is φ = 5627581332.

The previous prime is 6565511479. The next prime is 6565511573. The reversal of 6565511561 is 1651155656.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6565511561 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6565510561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 468965105 + ... + 468965118.

It is an arithmetic number, because the mean of its divisors is an integer number (1875860448).

Almost surely, 2^6565511561 is an apocalyptic number.

It is an amenable number.

6565511561 is a deficient number, since it is larger than the sum of its proper divisors (937930231).

6565511561 is an equidigital number, since it uses as much as digits as its factorization.

6565511561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 937930230.

The product of its digits is 135000, while the sum is 41.

The square root of 6565511561 is about 81027.8443561224. The cubic root of 6565511561 is about 1872.5044427979.

The spelling of 6565511561 in words is "six billion, five hundred sixty-five million, five hundred eleven thousand, five hundred sixty-one".