821205 has 64 divisors (see below), whose sum is σ = 1843200. Its totient is φ = 336960.

The previous prime is 821173. The next prime is 821207. The reversal of 821205 is 502128.

It is not a de Polignac number, because 821205 - 2⁵ = 821173 is a prime.

821205 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 10356 + ... + 10434.

It is an arithmetic number, because the mean of its divisors is an integer number (28800).

2⁸²¹²⁰⁵ is an apocalyptic number.

It is an amenable number.

821205 is an abundant number, since it is smaller than the sum of its proper divisors (1021995).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

821205 is a wasteful number, since it uses less digits than its factorization.

821205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111 (or 105 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 18.

The square root of 821205 is about 906.2036195028. The cubic root of 821205 is about 93.6448420901.

The spelling of 821205 in words is "eight hundred twenty-one thousand, two hundred five".