66557763662861 has 2 divisors, whose sum is σ = 66557763662862. Its totient is φ = 66557763662860.

The previous prime is 66557763662849. The next prime is 66557763662879. The reversal of 66557763662861 is 16826636775566.

66557763662861 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., 61008299829961 + 5549463832900 = 7810781^2 + 2355730^2 .

It is a cyclic number.

It is not a de Polignac number, because 66557763662861 - 2³⁰ = 66556689921037 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66557763668861) 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, 33278881831430 + 33278881831431.

It is an arithmetic number, because the mean of its divisors is an integer number (33278881831431).

Almost surely, 2^{66557763662861} is an apocalyptic number.

It is an amenable number.

66557763662861 is a deficient number, since it is larger than the sum of its proper divisors (1).

66557763662861 is an equidigital number, since it uses as much as digits as its factorization.

66557763662861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2743372800, while the sum is 74.

The spelling of 66557763662861 in words is "sixty-six trillion, five hundred fifty-seven billion, seven hundred sixty-three million, six hundred sixty-two thousand, eight hundred sixty-one".