66681020173 has 2 divisors, whose sum is σ = 66681020174. Its totient is φ = 66681020172.

The previous prime is 66681020113. The next prime is 66681020183. The reversal of 66681020173 is 37102018666.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66606318724 + 74701449 = 258082^2 + 8643^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66681020173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66681020113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33340510086 + 33340510087.

It is an arithmetic number, because the mean of its divisors is an integer number (33340510087).

Almost surely, 2^66681020173 is an apocalyptic number.

It is an amenable number.

66681020173 is a deficient number, since it is larger than the sum of its proper divisors (1).

66681020173 is an equidigital number, since it uses as much as digits as its factorization.

66681020173 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 40.

The spelling of 66681020173 in words is "sixty-six billion, six hundred eighty-one million, twenty thousand, one hundred seventy-three".