66640717687 has 4 divisors (see below), whose sum is σ = 66768627456. Its totient is φ = 66512807920.

The previous prime is 66640717681. The next prime is 66640717697. The reversal of 66640717687 is 78671704666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78671704666 = 2 ⋅39335852333.

It is a cyclic number.

It is not a de Polignac number, because 66640717687 - 2²⁷ = 66506499959 is a prime.

It is a super-3 number, since 3×66640717687³ (a number of 33 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66640717681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63954103 + ... + 63955144.

It is an arithmetic number, because the mean of its divisors is an integer number (16692156864).

Almost surely, 2^66640717687 is an apocalyptic number.

66640717687 is a deficient number, since it is larger than the sum of its proper divisors (127909769).

66640717687 is a wasteful number, since it uses less digits than its factorization.

66640717687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127909768.

The product of its (nonzero) digits is 14224896, while the sum is 58.

The spelling of 66640717687 in words is "sixty-six billion, six hundred forty million, seven hundred seventeen thousand, six hundred eighty-seven".