66981218989 has 2 divisors, whose sum is σ = 66981218990. Its totient is φ = 66981218988.

The previous prime is 66981218963. The next prime is 66981219043. The reversal of 66981218989 is 98981218966.

66981218989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 54452222500 + 12528996489 = 233350^2 + 111933^2 .

It is a cyclic number.

It is not a de Polignac number, because 66981218989 - 2⁵ = 66981218957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66981218939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33490609494 + 33490609495.

It is an arithmetic number, because the mean of its divisors is an integer number (33490609495).

Almost surely, 2^66981218989 is an apocalyptic number.

It is an amenable number.

66981218989 is a deficient number, since it is larger than the sum of its proper divisors (1).

66981218989 is an equidigital number, since it uses as much as digits as its factorization.

66981218989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26873856, while the sum is 67.

The spelling of 66981218989 in words is "sixty-six billion, nine hundred eighty-one million, two hundred eighteen thousand, nine hundred eighty-nine".