66663217 has 2 divisors, whose sum is σ = 66663218. Its totient is φ = 66663216.

The previous prime is 66663173. The next prime is 66663271. The reversal of 66663217 is 71236666.

Together with next prime (66663271) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66650896 + 12321 = 8164^2 + 111^2 .

It is a cyclic number.

It is not a de Polignac number, because 66663217 - 2²³ = 58274609 is a prime.

It is not a weakly prime, because it can be changed into another prime (66663017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33331608 + 33331609.

It is an arithmetic number, because the mean of its divisors is an integer number (33331609).

Almost surely, 2^66663217 is an apocalyptic number.

It is an amenable number.

66663217 is a deficient number, since it is larger than the sum of its proper divisors (1).

66663217 is an equidigital number, since it uses as much as digits as its factorization.

66663217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 37.

The square root of 66663217 is about 8164.7545584665. The cubic root of 66663217 is about 405.4731390611.

The spelling of 66663217 in words is "sixty-six million, six hundred sixty-three thousand, two hundred seventeen".