66561636340079 has 2 divisors, whose sum is σ = 66561636340080. Its totient is φ = 66561636340078.

The previous prime is 66561636340013. The next prime is 66561636340103. The reversal of 66561636340079 is 97004363616566.

66561636340079 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 is a cyclic number.

It is not a de Polignac number, because 66561636340079 - 2³² = 66557341372783 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66561636340379) 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, 33280818170039 + 33280818170040.

It is an arithmetic number, because the mean of its divisors is an integer number (33280818170040).

Almost surely, 2^{66561636340079} is an apocalyptic number.

66561636340079 is a deficient number, since it is larger than the sum of its proper divisors (1).

66561636340079 is an equidigital number, since it uses as much as digits as its factorization.

66561636340079 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 88179840, while the sum is 62.

The spelling of 66561636340079 in words is "sixty-six trillion, five hundred sixty-one billion, six hundred thirty-six million, three hundred forty thousand, seventy-nine".