66561416566 has 4 divisors (see below), whose sum is σ = 99842124852. Its totient is φ = 33280708282.

The previous prime is 66561416563. The next prime is 66561416639.

66561416566 is nontrivially palindromic in base 10.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66561416563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16640354140 + ... + 16640354143.

It is an arithmetic number, because the mean of its divisors is an integer number (24960531213).

Almost surely, 2^66561416566 is an apocalyptic number.

66561416566 is a deficient number, since it is larger than the sum of its proper divisors (33280708286).

66561416566 is a wasteful number, since it uses less digits than its factorization.

66561416566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33280708285.

The product of its digits is 4665600, while the sum is 52.

The spelling of 66561416566 in words is "sixty-six billion, five hundred sixty-one million, four hundred sixteen thousand, five hundred sixty-six".