66720439789 has 2 divisors, whose sum is σ = 66720439790. Its totient is φ = 66720439788.

The previous prime is 66720439757. The next prime is 66720439813. The reversal of 66720439789 is 98793402766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66587222025 + 133217764 = 258045^2 + 11542^2 .

It is a cyclic number.

It is not a de Polignac number, because 66720439789 - 2⁵ = 66720439757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66720439739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33360219894 + 33360219895.

It is an arithmetic number, because the mean of its divisors is an integer number (33360219895).

Almost surely, 2^66720439789 is an apocalyptic number.

It is an amenable number.

66720439789 is a deficient number, since it is larger than the sum of its proper divisors (1).

66720439789 is an equidigital number, since it uses as much as digits as its factorization.

66720439789 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27433728, while the sum is 61.

The spelling of 66720439789 in words is "sixty-six billion, seven hundred twenty million, four hundred thirty-nine thousand, seven hundred eighty-nine".