66218618 has 4 divisors (see below), whose sum is σ = 99327930. Its totient is φ = 33109308.

The previous prime is 66218617. The next prime is 66218639. The reversal of 66218618 is 81681266.

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., 65885689 + 332929 = 8117^2 + 577^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (66218617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16554653 + ... + 16554656.

Almost surely, 2^66218618 is an apocalyptic number.

66218618 is a deficient number, since it is larger than the sum of its proper divisors (33109312).

66218618 is a wasteful number, since it uses less digits than its factorization.

66218618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33109311.

The product of its digits is 27648, while the sum is 38.

The square root of 66218618 is about 8137.4822887672. The cubic root of 66218618 is about 404.5697162619.

The spelling of 66218618 in words is "sixty-six million, two hundred eighteen thousand, six hundred eighteen".