66654221 has 2 divisors, whose sum is σ = 66654222. Its totient is φ = 66654220.

The previous prime is 66654197. The next prime is 66654239. The reversal of 66654221 is 12245666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51638596 + 15015625 = 7186^2 + 3875^2 .

It is a cyclic number.

It is not a de Polignac number, because 66654221 - 2⁶ = 66654157 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

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 (66654251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33327110 + 33327111.

It is an arithmetic number, because the mean of its divisors is an integer number (33327111).

Almost surely, 2^66654221 is an apocalyptic number.

It is an amenable number.

66654221 is a deficient number, since it is larger than the sum of its proper divisors (1).

66654221 is an equidigital number, since it uses as much as digits as its factorization.

66654221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 32.

The square root of 66654221 is about 8164.2036353829. The cubic root of 66654221 is about 405.4548991150.

Adding to 66654221 its reverse (12245666), we get a palindrome (78899887).

The spelling of 66654221 in words is "sixty-six million, six hundred fifty-four thousand, two hundred twenty-one".