8421800921 has 4 divisors (see below), whose sum is σ = 8422201344. Its totient is φ = 8421400500.

The previous prime is 8421800909. The next prime is 8421800927. The reversal of 8421800921 is 1290081248.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8421800921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8421800927) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166805 + ... + 211346.

It is an arithmetic number, because the mean of its divisors is an integer number (2105550336).

Almost surely, 2^8421800921 is an apocalyptic number.

It is an amenable number.

8421800921 is a deficient number, since it is larger than the sum of its proper divisors (400423).

8421800921 is a wasteful number, since it uses less digits than its factorization.

8421800921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400422.

The product of its (nonzero) digits is 9216, while the sum is 35.

The square root of 8421800921 is about 91770.3706051142. The cubic root of 8421800921 is about 2034.5497957493.

The spelling of 8421800921 in words is "eight billion, four hundred twenty-one million, eight hundred thousand, nine hundred twenty-one".