820840 has 16 divisors (see below), whose sum is σ = 1846980. Its totient is φ = 328320.

The previous prime is 820837. The next prime is 820873. The reversal of 820840 is 48028.

It can be written as a sum of positive squares in 2 ways, for example, as 820836 + 4 = 906^2 + 2^2 .

It is a zygodrome in base 3.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10221 + ... + 10300.

2⁸²⁰⁸⁴⁰ is an apocalyptic number.

It is an amenable number.

820840 is an abundant number, since it is smaller than the sum of its proper divisors (1026140).

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

820840 is a wasteful number, since it uses less digits than its factorization.

820840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20532 (or 20528 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 820840 is about 906.0022075028. The cubic root of 820840 is about 93.6309659639.

Adding to 820840 its reverse (48028), we get a palindrome (868868).

The spelling of 820840 in words is "eight hundred twenty thousand, eight hundred forty".