66332221 has 2 divisors, whose sum is σ = 66332222. Its totient is φ = 66332220.

The previous prime is 66332197. The next prime is 66332237. The reversal of 66332221 is 12223366.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61795321 + 4536900 = 7861^2 + 2130^2 .

It is a cyclic number.

It is not a de Polignac number, because 66332221 - 2⁷ = 66332093 is a prime.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66332261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33166110 + 33166111.

It is an arithmetic number, because the mean of its divisors is an integer number (33166111).

Almost surely, 2^66332221 is an apocalyptic number.

It is an amenable number.

66332221 is a deficient number, since it is larger than the sum of its proper divisors (1).

66332221 is an equidigital number, since it uses as much as digits as its factorization.

66332221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2592, while the sum is 25.

The square root of 66332221 is about 8144.4595278017. The cubic root of 66332221 is about 404.8009406370.

Adding to 66332221 its reverse (12223366), we get a palindrome (78555587).

The spelling of 66332221 in words is "sixty-six million, three hundred thirty-two thousand, two hundred twenty-one".