66242221 has 2 divisors, whose sum is σ = 66242222. Its totient is φ = 66242220.

The previous prime is 66242207. The next prime is 66242237. The reversal of 66242221 is 12224266.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38564100 + 27678121 = 6210^2 + 5261^2 .

It is a cyclic number.

It is not a de Polignac number, because 66242221 - 2⁹ = 66241709 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66242201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33121110 + 33121111.

It is an arithmetic number, because the mean of its divisors is an integer number (33121111).

Almost surely, 2^66242221 is an apocalyptic number.

It is an amenable number.

66242221 is a deficient number, since it is larger than the sum of its proper divisors (1).

66242221 is an equidigital number, since it uses as much as digits as its factorization.

66242221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 25.

The square root of 66242221 is about 8138.9324238502. The cubic root of 66242221 is about 404.6177789014.

Adding to 66242221 its reverse (12224266), we get a palindrome (78466487).

The spelling of 66242221 in words is "sixty-six million, two hundred forty-two thousand, two hundred twenty-one".