66565715641 has 4 divisors (see below), whose sum is σ = 66864216832. Its totient is φ = 66267214452.

The previous prime is 66565715609. The next prime is 66565715653. The reversal of 66565715641 is 14651756566.

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 an emirpimes, since its reverse is a distinct semiprime: 14651756566 = 2 ⋅7325878283.

It is a cyclic number.

It is not a de Polignac number, because 66565715641 - 2⁵ = 66565715609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66565715941) 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, 149250261 + ... + 149250706.

It is an arithmetic number, because the mean of its divisors is an integer number (16716054208).

Almost surely, 2^66565715641 is an apocalyptic number.

It is an amenable number.

66565715641 is a deficient number, since it is larger than the sum of its proper divisors (298501191).

66565715641 is a wasteful number, since it uses less digits than its factorization.

66565715641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 298501190.

The product of its digits is 4536000, while the sum is 52.

The spelling of 66565715641 in words is "sixty-six billion, five hundred sixty-five million, seven hundred fifteen thousand, six hundred forty-one".