8001821 has 4 divisors (see below), whose sum is σ = 8084412. Its totient is φ = 7919232.

The previous prime is 8001811. The next prime is 8001823. The reversal of 8001821 is 1281008.

8001821 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 1473796 + 6528025 = 1214^2 + 2555^2 .

It is a cyclic number.

It is not a de Polignac number, because 8001821 - 2¹⁴ = 7985437 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 8001793 and 8001802.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8001823) 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, 41150 + ... + 41343.

It is an arithmetic number, because the mean of its divisors is an integer number (2021103).

Almost surely, 2^8001821 is an apocalyptic number.

It is an amenable number.

8001821 is a deficient number, since it is larger than the sum of its proper divisors (82591).

8001821 is an equidigital number, since it uses as much as digits as its factorization.

8001821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82590.

The product of its (nonzero) digits is 128, while the sum is 20.

The square root of 8001821 is about 2828.7490167917. The cubic root of 8001821 is about 200.0151738487.

Adding to 8001821 its reverse (1281008), we get a palindrome (9282829).

The spelling of 8001821 in words is "eight million, one thousand, eight hundred twenty-one".