66155775578 has 4 divisors (see below), whose sum is σ = 99233663370. Its totient is φ = 33077887788.

The previous prime is 66155775557. The next prime is 66155775607. The reversal of 66155775578 is 87557755166.

66155775578 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 46482066409 + 19673709169 = 215597^2 + 140263^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 66155775578.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16538943893 + ... + 16538943896.

Almost surely, 2^66155775578 is an apocalyptic number.

66155775578 is a deficient number, since it is larger than the sum of its proper divisors (33077887792).

66155775578 is a wasteful number, since it uses less digits than its factorization.

66155775578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33077887791.

The product of its digits is 61740000, while the sum is 62.

The spelling of 66155775578 in words is "sixty-six billion, one hundred fifty-five million, seven hundred seventy-five thousand, five hundred seventy-eight".