820240 has 20 divisors (see below), whose sum is σ = 1907244. Its totient is φ = 328064.

The previous prime is 820231. The next prime is 820241. The reversal of 820240 is 42028.

It can be written as a sum of positive squares in 2 ways, for example, as 186624 + 633616 = 432^2 + 796^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (820241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5047 + ... + 5206.

2⁸²⁰²⁴⁰ is an apocalyptic number.

820240 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

820240 is an abundant number, since it is smaller than the sum of its proper divisors (1087004).

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

820240 is a wasteful number, since it uses less digits than its factorization.

820240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10266 (or 10260 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 820240 is about 905.6710219500. The cubic root of 820240 is about 93.6081469520.

Adding to 820240 its reverse (42028), we get a palindrome (862268).

The spelling of 820240 in words is "eight hundred twenty thousand, two hundred forty".