666561572011 has 4 divisors (see below), whose sum is σ = 666572643000. Its totient is φ = 666550501024.

The previous prime is 666561571969. The next prime is 666561572021. The reversal of 666561572011 is 110275165666.

666561572011 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 666561572011 - 2¹⁵ = 666561539243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666561572021) 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, 5444686 + ... + 5565763.

It is an arithmetic number, because the mean of its divisors is an integer number (166643160750).

Almost surely, 2^666561572011 is an apocalyptic number.

666561572011 is a deficient number, since it is larger than the sum of its proper divisors (11070989).

666561572011 is a wasteful number, since it uses less digits than its factorization.

666561572011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11070988.

The product of its (nonzero) digits is 453600, while the sum is 46.

The spelling of 666561572011 in words is "six hundred sixty-six billion, five hundred sixty-one million, five hundred seventy-two thousand, eleven".