800021 has 6 divisors (see below), whose sum is σ = 817122. Its totient is φ = 783200.

The previous prime is 800011. The next prime is 800029. The reversal of 800021 is 120008.

It can be written as a sum of positive squares in 3 ways, for example, as 96100 + 703921 = 310^2 + 839^2 .

It is not a de Polignac number, because 800021 - 2¹⁸ = 537877 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 799975 and 800011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (800029) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7871 + ... + 7971.

It is an arithmetic number, because the mean of its divisors is an integer number (136187).

2⁸⁰⁰⁰²¹ is an apocalyptic number.

It is an amenable number.

800021 is a deficient number, since it is larger than the sum of its proper divisors (17101).

800021 is an equidigital number, since it uses as much as digits as its factorization.

800021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 279 (or 190 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 800021 is about 894.4389302798. The cubic root of 800021 is about 92.8325889432.

Adding to 800021 its reverse (120008), we get a palindrome (920029).

The spelling of 800021 in words is "eight hundred thousand, twenty-one".