6921889821 has 72 divisors (see below), whose sum is σ = 12866747712. Its totient is φ = 3507926400.

The previous prime is 6921889801. The next prime is 6921889823. The reversal of 6921889821 is 1289881296.

It is not a de Polignac number, because 6921889821 - 2⁹ = 6921889309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6921889823) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 301470 + ... + 323616.

Almost surely, 2^6921889821 is an apocalyptic number.

It is an amenable number.

6921889821 is a deficient number, since it is larger than the sum of its proper divisors (5944857891).

6921889821 is a wasteful number, since it uses less digits than its factorization.

6921889821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22223 (or 22209 counting only the distinct ones).

The product of its digits is 995328, while the sum is 54.

The square root of 6921889821 is about 83197.8955322789. The cubic root of 6921889821 is about 1905.7893428408.

The spelling of 6921889821 in words is "six billion, nine hundred twenty-one million, eight hundred eighty-nine thousand, eight hundred twenty-one".