66916181 has 2 divisors, whose sum is σ = 66916182. Its totient is φ = 66916180.

The previous prime is 66916159. The next prime is 66916189. The reversal of 66916181 is 18161966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66748900 + 167281 = 8170^2 + 409^2 .

It is a cyclic number.

It is not a de Polignac number, because 66916181 - 2¹⁴ = 66899797 is a prime.

It is a super-2 number, since 2×66916181² = 8955550559249522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66916189) 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, 33458090 + 33458091.

It is an arithmetic number, because the mean of its divisors is an integer number (33458091).

Almost surely, 2^66916181 is an apocalyptic number.

It is an amenable number.

66916181 is a deficient number, since it is larger than the sum of its proper divisors (1).

66916181 is an equidigital number, since it uses as much as digits as its factorization.

66916181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 38.

The square root of 66916181 is about 8180.2311092047. The cubic root of 66916181 is about 405.9853687691.

The spelling of 66916181 in words is "sixty-six million, nine hundred sixteen thousand, one hundred eighty-one".