66728385613 has 2 divisors, whose sum is σ = 66728385614. Its totient is φ = 66728385612.

The previous prime is 66728385587. The next prime is 66728385617. The reversal of 66728385613 is 31658382766.

66728385613 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53016444009 + 13711941604 = 230253^2 + 117098^2 .

It is a cyclic number.

It is not a de Polignac number, because 66728385613 - 2¹³ = 66728377421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66728385617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33364192806 + 33364192807.

It is an arithmetic number, because the mean of its divisors is an integer number (33364192807).

Almost surely, 2^66728385613 is an apocalyptic number.

It is an amenable number.

66728385613 is a deficient number, since it is larger than the sum of its proper divisors (1).

66728385613 is an equidigital number, since it uses as much as digits as its factorization.

66728385613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8709120, while the sum is 55.

The spelling of 66728385613 in words is "sixty-six billion, seven hundred twenty-eight million, three hundred eighty-five thousand, six hundred thirteen".