66965981 has 2 divisors, whose sum is σ = 66965982. Its totient is φ = 66965980.

The previous prime is 66965971. The next prime is 66966019. The reversal of 66965981 is 18956966.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44488900 + 22477081 = 6670^2 + 4741^2 .

It is a cyclic number.

It is not a de Polignac number, because 66965981 - 2⁶ = 66965917 is a prime.

It is a super-2 number, since 2×66965981² = 8968885222584722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66965971) 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, 33482990 + 33482991.

It is an arithmetic number, because the mean of its divisors is an integer number (33482991).

Almost surely, 2^66965981 is an apocalyptic number.

It is an amenable number.

66965981 is a deficient number, since it is larger than the sum of its proper divisors (1).

66965981 is an equidigital number, since it uses as much as digits as its factorization.

66965981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 699840, while the sum is 50.

The square root of 66965981 is about 8183.2744668623. The cubic root of 66965981 is about 406.0860572105.

The spelling of 66965981 in words is "sixty-six million, nine hundred sixty-five thousand, nine hundred eighty-one".