66220556617 has 2 divisors, whose sum is σ = 66220556618. Its totient is φ = 66220556616.

The previous prime is 66220556587. The next prime is 66220556653. The reversal of 66220556617 is 71665502266.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57813317136 + 8407239481 = 240444^2 + 91691^2 .

It is a cyclic number.

It is not a de Polignac number, because 66220556617 - 2³¹ = 64073072969 is a prime.

It is not a weakly prime, because it can be changed into another prime (66220556657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33110278308 + 33110278309.

It is an arithmetic number, because the mean of its divisors is an integer number (33110278309).

Almost surely, 2^66220556617 is an apocalyptic number.

It is an amenable number.

66220556617 is a deficient number, since it is larger than the sum of its proper divisors (1).

66220556617 is an equidigital number, since it uses as much as digits as its factorization.

66220556617 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 907200, while the sum is 46.

The spelling of 66220556617 in words is "sixty-six billion, two hundred twenty million, five hundred fifty-six thousand, six hundred seventeen".