66817853 has 2 divisors, whose sum is σ = 66817854. Its totient is φ = 66817852.

The previous prime is 66817831. The next prime is 66817867. The reversal of 66817853 is 35871866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62378404 + 4439449 = 7898^2 + 2107^2 .

It is a cyclic number.

It is not a de Polignac number, because 66817853 - 2¹⁰ = 66816829 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 (66817873) 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, 33408926 + 33408927.

It is an arithmetic number, because the mean of its divisors is an integer number (33408927).

Almost surely, 2^66817853 is an apocalyptic number.

It is an amenable number.

66817853 is a deficient number, since it is larger than the sum of its proper divisors (1).

66817853 is an equidigital number, since it uses as much as digits as its factorization.

66817853 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 44.

The square root of 66817853 is about 8174.2188005950. The cubic root of 66817853 is about 405.7864168979.

The spelling of 66817853 in words is "sixty-six million, eight hundred seventeen thousand, eight hundred fifty-three".