66666361 has 2 divisors, whose sum is σ = 66666362. Its totient is φ = 66666360.

The previous prime is 66666359. The next prime is 66666371. The reversal of 66666361 is 16366666.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 59675625 + 6990736 = 7725^2 + 2644^2 .

It is a cyclic number.

It is not a de Polignac number, because 66666361 - 2¹ = 66666359 is a prime.

Together with 66666359, it forms a pair of twin primes.

It is a zygodrome in base 3.

It is not a weakly prime, because it can be changed into another prime (66666311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33333180 + 33333181.

It is an arithmetic number, because the mean of its divisors is an integer number (33333181).

Almost surely, 2^66666361 is an apocalyptic number.

It is an amenable number.

66666361 is a deficient number, since it is larger than the sum of its proper divisors (1).

66666361 is an equidigital number, since it uses as much as digits as its factorization.

66666361 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 139968, while the sum is 40.

The square root of 66666361 is about 8164.9470910717. The cubic root of 66666361 is about 405.4795133285.

The spelling of 66666361 in words is "sixty-six million, six hundred sixty-six thousand, three hundred sixty-one".