66571221 has 8 divisors (see below), whose sum is σ = 89640864. Its totient is φ = 43941200.

The previous prime is 66571217. The next prime is 66571237. The reversal of 66571221 is 12217566.

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

It is a cyclic number.

It is not a de Polignac number, because 66571221 - 2² = 66571217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66571261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 109551 + ... + 110156.

It is an arithmetic number, because the mean of its divisors is an integer number (11205108).

Almost surely, 2^66571221 is an apocalyptic number.

It is an amenable number.

66571221 is a deficient number, since it is larger than the sum of its proper divisors (23069643).

66571221 is a wasteful number, since it uses less digits than its factorization.

66571221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219811.

The product of its digits is 5040, while the sum is 30.

The square root of 66571221 is about 8159.1188862524. The cubic root of 66571221 is about 405.2865340098.

Adding to 66571221 its reverse (12217566), we get a palindrome (78788787).

The spelling of 66571221 in words is "sixty-six million, five hundred seventy-one thousand, two hundred twenty-one".