8645821 has 4 divisors (see below), whose sum is σ = 8690812. Its totient is φ = 8600832.

The previous prime is 8645803. The next prime is 8645849. The reversal of 8645821 is 1285468.

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 2325625 + 6320196 = 1525^2 + 2514^2 .

It is a cyclic number.

It is not a de Polignac number, because 8645821 - 2⁵ = 8645789 is a prime.

It is a Duffinian number.

8645821 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8643821) 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, 22206 + ... + 22591.

It is an arithmetic number, because the mean of its divisors is an integer number (2172703).

Almost surely, 2^8645821 is an apocalyptic number.

It is an amenable number.

8645821 is a deficient number, since it is larger than the sum of its proper divisors (44991).

8645821 is a wasteful number, since it uses less digits than its factorization.

8645821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44990.

The product of its digits is 15360, while the sum is 34.

The square root of 8645821 is about 2940.3776968274. The cubic root of 8645821 is about 205.2431855246.

The spelling of 8645821 in words is "eight million, six hundred forty-five thousand, eight hundred twenty-one".