66006221 has 2 divisors, whose sum is σ = 66006222. Its totient is φ = 66006220.

The previous prime is 66006203. The next prime is 66006263. The reversal of 66006221 is 12260066.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45630025 + 20376196 = 6755^2 + 4514^2 .

It is a cyclic number.

It is not a de Polignac number, because 66006221 - 2¹⁴ = 65989837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66006271) 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 as a sum of consecutive naturals, namely, 33003110 + 33003111.

It is an arithmetic number, because the mean of its divisors is an integer number (33003111).

Almost surely, 2^66006221 is an apocalyptic number.

It is an amenable number.

66006221 is a deficient number, since it is larger than the sum of its proper divisors (1).

66006221 is an equidigital number, since it uses as much as digits as its factorization.

66006221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 66006221 is about 8124.4212716968. The cubic root of 66006221 is about 404.1366989129.

Adding to 66006221 its reverse (12260066), we get a palindrome (78266287).

It can be divided in two parts, 6600 and 6221, that added together give a palindrome (12821).

The spelling of 66006221 in words is "sixty-six million, six thousand, two hundred twenty-one".