8204821 has 4 divisors (see below), whose sum is σ = 8297100. Its totient is φ = 8112544.

The previous prime is 8204809. The next prime is 8204843. The reversal of 8204821 is 1284028.

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 2937796 + 5267025 = 1714^2 + 2295^2 .

It is a cyclic number.

It is not a de Polignac number, because 8204821 - 2¹⁷ = 8073749 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8204851) 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, 46006 + ... + 46183.

It is an arithmetic number, because the mean of its divisors is an integer number (2074275).

Almost surely, 2^8204821 is an apocalyptic number.

It is an amenable number.

8204821 is a deficient number, since it is larger than the sum of its proper divisors (92279).

8204821 is an equidigital number, since it uses as much as digits as its factorization.

8204821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92278.

The product of its (nonzero) digits is 1024, while the sum is 25.

The square root of 8204821 is about 2864.4058720789. The cubic root of 8204821 is about 201.6924788428.

Adding to 8204821 its reverse (1284028), we get a palindrome (9488849).

It can be divided in two parts, 8204 and 821, that added together give a square (9025 = 95²).

The spelling of 8204821 in words is "eight million, two hundred four thousand, eight hundred twenty-one".