66208795981 has 2 divisors, whose sum is σ = 66208795982. Its totient is φ = 66208795980.

The previous prime is 66208795943. The next prime is 66208796009. The reversal of 66208795981 is 18959780266.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37092834025 + 29115961956 = 192595^2 + 170634^2 .

It is a cyclic number.

It is not a de Polignac number, because 66208795981 - 2⁷ = 66208795853 is a prime.

It is a super-2 number, since 2×66208795981² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66208735981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33104397990 + 33104397991.

It is an arithmetic number, because the mean of its divisors is an integer number (33104397991).

Almost surely, 2^66208795981 is an apocalyptic number.

It is an amenable number.

66208795981 is a deficient number, since it is larger than the sum of its proper divisors (1).

66208795981 is an equidigital number, since it uses as much as digits as its factorization.

66208795981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13063680, while the sum is 61.

The spelling of 66208795981 in words is "sixty-six billion, two hundred eight million, seven hundred ninety-five thousand, nine hundred eighty-one".