66155780517 has 8 divisors (see below), whose sum is σ = 93396396096. Its totient is φ = 41509509312.

The previous prime is 66155780507. The next prime is 66155780521. The reversal of 66155780517 is 71508755166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66155780517 - 2⁷ = 66155780389 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51), and also a Moran number because the ratio is a prime number: 1297172167 = 66155780517 / (6 + 6 + 1 + 5 + 5 + 7 + 8 + 0 + 5 + 1 + 7).

It is a self number, because there is not a number n which added to its sum of digits gives 66155780517.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66155780507) 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 7 ways as a sum of consecutive naturals, for example, 648586033 + ... + 648586134.

It is an arithmetic number, because the mean of its divisors is an integer number (11674549512).

Almost surely, 2^66155780517 is an apocalyptic number.

It is an amenable number.

66155780517 is a deficient number, since it is larger than the sum of its proper divisors (27240615579).

66155780517 is a wasteful number, since it uses less digits than its factorization.

66155780517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1297172187.

The product of its (nonzero) digits is 1764000, while the sum is 51.

The spelling of 66155780517 in words is "sixty-six billion, one hundred fifty-five million, seven hundred eighty thousand, five hundred seventeen".