66518772017 has 4 divisors (see below), whose sum is σ = 66519405300. Its totient is φ = 66518138736.

The previous prime is 66518771999. The next prime is 66518772049. The reversal of 66518772017 is 71027781566.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 58234859761 + 8283912256 = 241319^2 + 91016^2 .

It is a cyclic number.

It is not a de Polignac number, because 66518772017 - 2¹⁶ = 66518706481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66518772317) 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, 117218 + ... + 383115.

It is an arithmetic number, because the mean of its divisors is an integer number (16629851325).

Almost surely, 2^66518772017 is an apocalyptic number.

It is an amenable number.

66518772017 is a deficient number, since it is larger than the sum of its proper divisors (633283).

66518772017 is a wasteful number, since it uses less digits than its factorization.

66518772017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 633282.

The product of its (nonzero) digits is 987840, while the sum is 50.

The spelling of 66518772017 in words is "sixty-six billion, five hundred eighteen million, seven hundred seventy-two thousand, seventeen".