820820 has 96 divisors (see below), whose sum is σ = 2370816. Its totient is φ = 230400.

The previous prime is 820793. The next prime is 820837. The reversal of 820820 is 28028.

820820 = T₇₀ + T₇₁ + ... + T₁₇₃.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an Ulam number.

It is a nialpdrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 820792 and 820801.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20000 + ... + 20040.

It is an arithmetic number, because the mean of its divisors is an integer number (24696).

2⁸²⁰⁸²⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 820820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1185408).

820820 is an abundant number, since it is smaller than the sum of its proper divisors (1549996).

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

820820 is a wasteful number, since it uses less digits than its factorization.

820820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81 (or 79 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 820820 is about 905.9911699349. The cubic root of 820820 is about 93.6302055094.

820820 divided by its sum of digits (20) gives a triangular number (41041 = T₂₈₆).

Adding to 820820 its reverse (28028), we get a palindrome (848848).

It can be divided in two parts, 8208 and 20, that added together give a palindrome (8228).

The spelling of 820820 in words is "eight hundred twenty thousand, eight hundred twenty".