66655361561 has 2 divisors, whose sum is σ = 66655361562. Its totient is φ = 66655361560.

The previous prime is 66655361519. The next prime is 66655361567. The reversal of 66655361561 is 16516355666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64747855936 + 1907505625 = 254456^2 + 43675^2 .

It is a cyclic number.

It is not a de Polignac number, because 66655361561 - 2²² = 66651167257 is a prime.

It is not a weakly prime, because it can be changed into another prime (66655361567) 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, 33327680780 + 33327680781.

It is an arithmetic number, because the mean of its divisors is an integer number (33327680781).

Almost surely, 2^66655361561 is an apocalyptic number.

It is an amenable number.

66655361561 is a deficient number, since it is larger than the sum of its proper divisors (1).

66655361561 is an equidigital number, since it uses as much as digits as its factorization.

66655361561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2916000, while the sum is 50.

The spelling of 66655361561 in words is "sixty-six billion, six hundred fifty-five million, three hundred sixty-one thousand, five hundred sixty-one".