66716823617 has 2 divisors, whose sum is σ = 66716823618. Its totient is φ = 66716823616.

The previous prime is 66716823601. The next prime is 66716823623. The reversal of 66716823617 is 71632861766.

It is a Cunningham number, because it is equal to 258296²+1.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66716823616 + 1 = 258296^2 + 1^2 .

It is a cyclic number.

It is not a de Polignac number, because 66716823617 - 2⁴ = 66716823601 is a prime.

It is a super-2 number, since 2×66716823617² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66716823637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33358411808 + 33358411809.

It is an arithmetic number, because the mean of its divisors is an integer number (33358411809).

Almost surely, 2^66716823617 is an apocalyptic number.

It is an amenable number.

66716823617 is a deficient number, since it is larger than the sum of its proper divisors (1).

66716823617 is an equidigital number, since it uses as much as digits as its factorization.

66716823617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3048192, while the sum is 53.

The spelling of 66716823617 in words is "sixty-six billion, seven hundred sixteen million, eight hundred twenty-three thousand, six hundred seventeen".