66143645221165 has 4 divisors (see below), whose sum is σ = 79372374265404. Its totient is φ = 52914916176928.

The previous prime is 66143645221117. The next prime is 66143645221189. The reversal of 66143645221165 is 56112254634166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 46315674135844 + 19827971085321 = 6805562^2 + 4452861^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66143645221165 is a prime.

It is a Duffinian number.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 6614364522112 + ... + 6614364522121.

It is an arithmetic number, because the mean of its divisors is an integer number (19843093566351).

Almost surely, 2^{66143645221165} is an apocalyptic number.

It is an amenable number.

66143645221165 is a deficient number, since it is larger than the sum of its proper divisors (13228729044239).

66143645221165 is a wasteful number, since it uses less digits than its factorization.

66143645221165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13228729044238.

The product of its digits is 6220800, while the sum is 52.

The spelling of 66143645221165 in words is "sixty-six trillion, one hundred forty-three billion, six hundred forty-five million, two hundred twenty-one thousand, one hundred sixty-five".