66840804109 has 2 divisors, whose sum is σ = 66840804110. Its totient is φ = 66840804108.

The previous prime is 66840804073. The next prime is 66840804127. The reversal of 66840804109 is 90140804866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 65217922884 + 1622881225 = 255378^2 + 40285^2 .

It is a cyclic number.

It is not a de Polignac number, because 66840804109 - 2⁹ = 66840803597 is a prime.

It is a super-2 number, since 2×66840804109² (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 (66840804179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33420402054 + 33420402055.

It is an arithmetic number, because the mean of its divisors is an integer number (33420402055).

Almost surely, 2^66840804109 is an apocalyptic number.

It is an amenable number.

66840804109 is a deficient number, since it is larger than the sum of its proper divisors (1).

66840804109 is an equidigital number, since it uses as much as digits as its factorization.

66840804109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 331776, while the sum is 46.

The spelling of 66840804109 in words is "sixty-six billion, eight hundred forty million, eight hundred four thousand, one hundred nine".