66664221 has 8 divisors (see below), whose sum is σ = 95723040. Its totient is φ = 41024112.

The previous prime is 66664211. The next prime is 66664223. The reversal of 66664221 is 12246666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66664221 - 2⁷ = 66664093 is a prime.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66664223) 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 7 ways as a sum of consecutive naturals, for example, 854631 + ... + 854708.

It is an arithmetic number, because the mean of its divisors is an integer number (11965380).

Almost surely, 2^66664221 is an apocalyptic number.

It is an amenable number.

66664221 is a deficient number, since it is larger than the sum of its proper divisors (29058819).

66664221 is a wasteful number, since it uses less digits than its factorization.

66664221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1709355.

The product of its digits is 20736, while the sum is 33.

The square root of 66664221 is about 8164.8160420183. The cubic root of 66664221 is about 405.4751746314.

The spelling of 66664221 in words is "sixty-six million, six hundred sixty-four thousand, two hundred twenty-one".