820121 has 4 divisors (see below), whose sum is σ = 831744. Its totient is φ = 808500.

The previous prime is 820117. The next prime is 820129. The reversal of 820121 is 121028.

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 not a de Polignac number, because 820121 - 2² = 820117 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 820096 and 820105.

It is not an unprimeable number, because it can be changed into a prime (820129) 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, 5705 + ... + 5846.

It is an arithmetic number, because the mean of its divisors is an integer number (207936).

2⁸²⁰¹²¹ is an apocalyptic number.

It is an amenable number.

820121 is a deficient number, since it is larger than the sum of its proper divisors (11623).

820121 is a wasteful number, since it uses less digits than its factorization.

820121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11622.

The product of its (nonzero) digits is 32, while the sum is 14.

The square root of 820121 is about 905.6053224225. The cubic root of 820121 is about 93.6036198590.

Adding to 820121 its reverse (121028), we get a palindrome (941149).

The spelling of 820121 in words is "eight hundred twenty thousand, one hundred twenty-one".