66556618 has 16 divisors (see below), whose sum is σ = 104386176. Its totient is φ = 31767120.

The previous prime is 66556613. The next prime is 66556619. The reversal of 66556618 is 81665566.

It is not an unprimeable number, because it can be changed into a prime (66556613) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27880 + ... + 30172.

It is an arithmetic number, because the mean of its divisors is an integer number (6524136).

Almost surely, 2^66556618 is an apocalyptic number.

66556618 is a deficient number, since it is larger than the sum of its proper divisors (37829558).

66556618 is a wasteful number, since it uses less digits than its factorization.

66556618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2949.

The product of its digits is 259200, while the sum is 43.

The square root of 66556618 is about 8158.2239488751. The cubic root of 66556618 is about 405.2568974192.

The spelling of 66556618 in words is "sixty-six million, five hundred fifty-six thousand, six hundred eighteen".