66728169109 has 4 divisors (see below), whose sum is σ = 76260764704. Its totient is φ = 57195573516.

The previous prime is 66728169107. The next prime is 66728169133. The reversal of 66728169109 is 90196182766.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66728169109 - 2¹ = 66728169107 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66728169109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66728169107) 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 in 3 ways as a sum of consecutive naturals, for example, 4766297787 + ... + 4766297800.

It is an arithmetic number, because the mean of its divisors is an integer number (19065191176).

Almost surely, 2^66728169109 is an apocalyptic number.

It is an amenable number.

66728169109 is a deficient number, since it is larger than the sum of its proper divisors (9532595595).

66728169109 is an equidigital number, since it uses as much as digits as its factorization.

66728169109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9532595594.

The product of its (nonzero) digits is 1959552, while the sum is 55.

The spelling of 66728169109 in words is "sixty-six billion, seven hundred twenty-eight million, one hundred sixty-nine thousand, one hundred nine".