66500556181 has 2 divisors, whose sum is σ = 66500556182. Its totient is φ = 66500556180.

The previous prime is 66500556163. The next prime is 66500556203. The reversal of 66500556181 is 18165500566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 56922802225 + 9577753956 = 238585^2 + 97866^2 .

It is a cyclic number.

It is not a de Polignac number, because 66500556181 - 2¹⁷ = 66500425109 is a prime.

It is a super-2 number, since 2×66500556181² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66500656181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33250278090 + 33250278091.

It is an arithmetic number, because the mean of its divisors is an integer number (33250278091).

Almost surely, 2^66500556181 is an apocalyptic number.

It is an amenable number.

66500556181 is a deficient number, since it is larger than the sum of its proper divisors (1).

66500556181 is an equidigital number, since it uses as much as digits as its factorization.

66500556181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216000, while the sum is 43.

The spelling of 66500556181 in words is "sixty-six billion, five hundred million, five hundred fifty-six thousand, one hundred eighty-one".