840004020 has 60 divisors (see below), whose sum is σ = 2635128804. Its totient is φ = 224000640.

The previous prime is 840004013. The next prime is 840004021. The reversal of 840004020 is 20400048.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 661621284 + 178382736 = 25722^2 + 13356^2 .

It is a tau number, because it is divible by the number of its divisors (60).

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

It is a junction number, because it is equal to n+sod(n) for n = 840003984 and 840004002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (840004021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 257641 + ... + 260880.

Almost surely, 2^840004020 is an apocalyptic number.

It is an amenable number.

840004020 is an abundant number, since it is smaller than the sum of its proper divisors (1795124784).

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

840004020 is a wasteful number, since it uses less digits than its factorization.

840004020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 518542 (or 518531 counting only the distinct ones).

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

The square root of 840004020 is about 28982.8228438846. The cubic root of 840004020 is about 943.5403012299.

Adding to 840004020 its reverse (20400048), we get a palindrome (860404068).

The spelling of 840004020 in words is "eight hundred forty million, four thousand, twenty".