820440 has 96 divisors (see below), whose sum is σ = 2779920. Its totient is φ = 209664.

The previous prime is 820429. The next prime is 820441. The reversal of 820440 is 44028.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820441) by changing a digit.

820440 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15454 + ... + 15506.

2⁸²⁰⁴⁴⁰ 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 820440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1389960).

820440 is an abundant number, since it is smaller than the sum of its proper divisors (1959480).

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

820440 is a wasteful number, since it uses less digits than its factorization.

820440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113 (or 106 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 820440 is about 905.7814305891. The cubic root of 820440 is about 93.6157545254.

Adding to 820440 its reverse (44028), we get a palindrome (864468).

The spelling of 820440 in words is "eight hundred twenty thousand, four hundred forty".