66564561611 has 4 divisors (see below), whose sum is σ = 66593900400. Its totient is φ = 66535222824.

The previous prime is 66564561593. The next prime is 66564561673. The reversal of 66564561611 is 11616546566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66564561611 is a prime.

It is a super-2 number, since 2×66564561611² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66564561311) 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, 14665991 + ... + 14670528.

It is an arithmetic number, because the mean of its divisors is an integer number (16648475100).

Almost surely, 2^66564561611 is an apocalyptic number.

66564561611 is a deficient number, since it is larger than the sum of its proper divisors (29338789).

66564561611 is a wasteful number, since it uses less digits than its factorization.

66564561611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29338788.

The product of its digits is 777600, while the sum is 47.

The spelling of 66564561611 in words is "sixty-six billion, five hundred sixty-four million, five hundred sixty-one thousand, six hundred eleven".