66571321 has 4 divisors (see below), whose sum is σ = 66638052. Its totient is φ = 66504592.

The previous prime is 66571301. The next prime is 66571343. The reversal of 66571321 is 12317566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12317566 = 2 ⋅6158783.

It can be written as a sum of positive squares in 2 ways, for example, as 6431296 + 60140025 = 2536^2 + 7755^2 .

It is a cyclic number.

It is not a de Polignac number, because 66571321 - 2¹¹ = 66569273 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66571301) 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, 31846 + ... + 33871.

It is an arithmetic number, because the mean of its divisors is an integer number (16659513).

Almost surely, 2^66571321 is an apocalyptic number.

It is an amenable number.

66571321 is a deficient number, since it is larger than the sum of its proper divisors (66731).

66571321 is a wasteful number, since it uses less digits than its factorization.

66571321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66730.

The product of its digits is 7560, while the sum is 31.

The square root of 66571321 is about 8159.1250143628. The cubic root of 66571321 is about 405.2867369435.

Adding to 66571321 its reverse (12317566), we get a palindrome (78888887).

The spelling of 66571321 in words is "sixty-six million, five hundred seventy-one thousand, three hundred twenty-one".