66681891050 has 12 divisors (see below), whose sum is σ = 124028317446. Its totient is φ = 26672756400.

The previous prime is 66681891041. The next prime is 66681891083. The reversal of 66681891050 is 5019818666.

It can be written as a sum of positive squares in 3 ways, for example, as 64902148081 + 1779742969 = 254759^2 + 42187^2 .

It is a Harshad number since it is a multiple of its sum of digits (50), and also a Moran number because the ratio is a prime number: 1333637821 = 66681891050 / (6 + 6 + 6 + 8 + 1 + 8 + 9 + 1 + 0 + 5 + 0).

It is a self number, because there is not a number n which added to its sum of digits gives 66681891050.

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 666818861 + ... + 666818960.

Almost surely, 2^66681891050 is an apocalyptic number.

66681891050 is a deficient number, since it is larger than the sum of its proper divisors (57346426396).

66681891050 is a wasteful number, since it uses less digits than its factorization.

66681891050 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333637833 (or 1333637828 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 50.

The spelling of 66681891050 in words is "sixty-six billion, six hundred eighty-one million, eight hundred ninety-one thousand, fifty".