66561150661 has 4 divisors (see below), whose sum is σ = 67040008000. Its totient is φ = 66082293324.

The previous prime is 66561150653. The next prime is 66561150673. The reversal of 66561150661 is 16605116566.

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 not a de Polignac number, because 66561150661 - 2³ = 66561150653 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 (66561150631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 239428461 + ... + 239428738.

It is an arithmetic number, because the mean of its divisors is an integer number (16760002000).

Almost surely, 2^66561150661 is an apocalyptic number.

It is an amenable number.

66561150661 is a deficient number, since it is larger than the sum of its proper divisors (478857339).

66561150661 is a wasteful number, since it uses less digits than its factorization.

66561150661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478857338.

The product of its (nonzero) digits is 194400, while the sum is 43.

The spelling of 66561150661 in words is "sixty-six billion, five hundred sixty-one million, one hundred fifty thousand, six hundred sixty-one".