66564516001 has 27 divisors (see below), whose sum is σ = 72399600819. Its totient is φ = 61189581168.

The previous prime is 66564515999. The next prime is 66564516019. The reversal of 66564516001 is 10061546566.

The square root of 66564516001 is 258001.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 59562843025 + 7001672976 = 244055^2 + 83676^2 .

It is not a de Polignac number, because 66564516001 - 2¹ = 66564515999 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66564516071) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 181374520 + ... + 181374886.

It is an arithmetic number, because the mean of its divisors is an integer number (2681466697).

Almost surely, 2^66564516001 is an apocalyptic number.

66564516001 is the 258001-st square number.

66564516001 is the 129001-st centered octagonal number.

It is an amenable number.

66564516001 is a deficient number, since it is larger than the sum of its proper divisors (5835084818).

66564516001 is an frugal number, since it uses more digits than its factorization.

66564516001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 846 (or 423 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 40.

The spelling of 66564516001 in words is "sixty-six billion, five hundred sixty-four million, five hundred sixteen thousand, one".