66557916678 has 32 divisors (see below), whose sum is σ = 145346060160. Its totient is φ = 20151178560.

The previous prime is 66557916671. The next prime is 66557916703. The reversal of 66557916678 is 87661975566.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66557916671) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 372100 + ... + 521127.

It is an arithmetic number, because the mean of its divisors is an integer number (4542064380).

Almost surely, 2^66557916678 is an apocalyptic number.

66557916678 is an abundant number, since it is smaller than the sum of its proper divisors (78788143482).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66557916678 is a wasteful number, since it uses less digits than its factorization.

66557916678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 894372.

The product of its digits is 114307200, while the sum is 66.

The spelling of 66557916678 in words is "sixty-six billion, five hundred fifty-seven million, nine hundred sixteen thousand, six hundred seventy-eight".