1643821416685 has 32 divisors (see below), whose sum is σ = 2309511439872. Its totient is φ = 1099631339520.

The previous prime is 1643821416661. The next prime is 1643821416691. The reversal of 1643821416685 is 5866141283461.

It is not a de Polignac number, because 1643821416685 - 2³⁵ = 1609461678317 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 35819064 + ... + 35864926.

It is an arithmetic number, because the mean of its divisors is an integer number (72172232496).

Almost surely, 2^{1643821416685} is an apocalyptic number.

It is an amenable number.

1643821416685 is a deficient number, since it is larger than the sum of its proper divisors (665690023187).

1643821416685 is a wasteful number, since it uses less digits than its factorization.

1643821416685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 70893.

The product of its digits is 6635520, while the sum is 55.

The spelling of 1643821416685 in words is "one trillion, six hundred forty-three billion, eight hundred twenty-one million, four hundred sixteen thousand, six hundred eighty-five".