66218909 has 4 divisors (see below), whose sum is σ = 69098016. Its totient is φ = 63339804.

The previous prime is 66218903. The next prime is 66218921. The reversal of 66218909 is 90981266.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66218909 - 2⁸ = 66218653 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66218903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1439519 + ... + 1439564.

It is an arithmetic number, because the mean of its divisors is an integer number (17274504).

Almost surely, 2^66218909 is an apocalyptic number.

It is an amenable number.

66218909 is a deficient number, since it is larger than the sum of its proper divisors (2879107).

66218909 is a wasteful number, since it uses less digits than its factorization.

66218909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2879106.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 66218909 is about 8137.5001689708. The cubic root of 66218909 is about 404.5703088929.

The spelling of 66218909 in words is "sixty-six million, two hundred eighteen thousand, nine hundred nine".