66147217 has 2 divisors, whose sum is σ = 66147218. Its totient is φ = 66147216.

The previous prime is 66147163. The next prime is 66147239. The reversal of 66147217 is 71274166.

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., 57093136 + 9054081 = 7556^2 + 3009^2 .

It is a cyclic number.

It is not a de Polignac number, because 66147217 - 2⁷ = 66147089 is a prime.

It is not a weakly prime, because it can be changed into another prime (66147247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33073608 + 33073609.

It is an arithmetic number, because the mean of its divisors is an integer number (33073609).

Almost surely, 2^66147217 is an apocalyptic number.

It is an amenable number.

66147217 is a deficient number, since it is larger than the sum of its proper divisors (1).

66147217 is an equidigital number, since it uses as much as digits as its factorization.

66147217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14112, while the sum is 34.

The square root of 66147217 is about 8133.0939377337. The cubic root of 66147217 is about 404.4242532896.

It can be divided in two parts, 6614 and 7217, that added together give a palindrome (13831).

The spelling of 66147217 in words is "sixty-six million, one hundred forty-seven thousand, two hundred seventeen".