66631885813 has 2 divisors, whose sum is σ = 66631885814. Its totient is φ = 66631885812.

The previous prime is 66631885787. The next prime is 66631885843. The reversal of 66631885813 is 31858813666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61354299204 + 5277586609 = 247698^2 + 72647^2 .

It is a cyclic number.

It is not a de Polignac number, because 66631885813 - 2⁹ = 66631885301 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66631885843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33315942906 + 33315942907.

It is an arithmetic number, because the mean of its divisors is an integer number (33315942907).

Almost surely, 2^66631885813 is an apocalyptic number.

It is an amenable number.

66631885813 is a deficient number, since it is larger than the sum of its proper divisors (1).

66631885813 is an equidigital number, since it uses as much as digits as its factorization.

66631885813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4976640, while the sum is 55.

The spelling of 66631885813 in words is "sixty-six billion, six hundred thirty-one million, eight hundred eighty-five thousand, eight hundred thirteen".