66653221 has 2 divisors, whose sum is σ = 66653222. Its totient is φ = 66653220.

The previous prime is 66653203. The next prime is 66653227. The reversal of 66653221 is 12235666.

66653221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65788321 + 864900 = 8111^2 + 930^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66653221 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 (66653227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33326610 + 33326611.

It is an arithmetic number, because the mean of its divisors is an integer number (33326611).

Almost surely, 2^66653221 is an apocalyptic number.

It is an amenable number.

66653221 is a deficient number, since it is larger than the sum of its proper divisors (1).

66653221 is an equidigital number, since it uses as much as digits as its factorization.

66653221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 31.

The square root of 66653221 is about 8164.1423921928. The cubic root of 66653221 is about 405.4528714518.

Adding to 66653221 its reverse (12235666), we get a palindrome (78888887).

The spelling of 66653221 in words is "sixty-six million, six hundred fifty-three thousand, two hundred twenty-one".