66761139209 has 2 divisors, whose sum is σ = 66761139210. Its totient is φ = 66761139208.

The previous prime is 66761139197. The next prime is 66761139217. The reversal of 66761139209 is 90293116766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59331216400 + 7429922809 = 243580^2 + 86197^2 .

It is a cyclic number.

It is not a de Polignac number, because 66761139209 - 2¹² = 66761135113 is a prime.

It is not a weakly prime, because it can be changed into another prime (66761139239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33380569604 + 33380569605.

It is an arithmetic number, because the mean of its divisors is an integer number (33380569605).

Almost surely, 2^66761139209 is an apocalyptic number.

It is an amenable number.

66761139209 is a deficient number, since it is larger than the sum of its proper divisors (1).

66761139209 is an equidigital number, since it uses as much as digits as its factorization.

66761139209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 734832, while the sum is 50.

The spelling of 66761139209 in words is "sixty-six billion, seven hundred sixty-one million, one hundred thirty-nine thousand, two hundred nine".