20921680846 has 16 divisors (see below), whose sum is σ = 34243009200. Its totient is φ = 9507762880.

The previous prime is 20921680841. The next prime is 20921680891. The reversal of 20921680846 is 64808612902.

20921680846 is a nontrivial binomial coefficient, being equal to C(204557, 2).

It is a junction number, because it is equal to n+sod(n) for n = 20921680796 and 20921680805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20921680841) 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 7 ways as a sum of consecutive naturals, for example, 1 + ... + 204556.

It is an arithmetic number, because the mean of its divisors is an integer number (2140188075).

Almost surely, 2^20921680846 is an apocalyptic number.

20921680846 is the 204556-th triangular number.

20921680846 is the 68186-th centered nonagonal number.

20921680846 is a deficient number, since it is larger than the sum of its proper divisors (13321328354).

20921680846 is a wasteful number, since it uses less digits than its factorization.

20921680846 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 209219.

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

The spelling of 20921680846 in words is "twenty billion, nine hundred twenty-one million, six hundred eighty thousand, eight hundred forty-six".