66204345661 has 4 divisors (see below), whose sum is σ = 66204894112. Its totient is φ = 66203797212.

The previous prime is 66204345629. The next prime is 66204345673. The reversal of 66204345661 is 16654340266.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 66204345661 - 2⁵ = 66204345629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66204345061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5151 + ... + 363916.

It is an arithmetic number, because the mean of its divisors is an integer number (16551223528).

Almost surely, 2^66204345661 is an apocalyptic number.

It is an amenable number.

66204345661 is a deficient number, since it is larger than the sum of its proper divisors (548451).

66204345661 is a wasteful number, since it uses less digits than its factorization.

66204345661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 548450.

The product of its (nonzero) digits is 622080, while the sum is 43.

The spelling of 66204345661 in words is "sixty-six billion, two hundred four million, three hundred forty-five thousand, six hundred sixty-one".