840420 has 144 divisors (see below), whose sum is σ = 3144960. Its totient is φ = 177408.

The previous prime is 840353. The next prime is 840439. The reversal of 840420 is 24048.

It is a happy number.

840420 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 = 840393 and 840402.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 28966 + ... + 28994.

It is an arithmetic number, because the mean of its divisors is an integer number (21840).

2⁸⁴⁰⁴²⁰ 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 840420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1572480).

840420 is an abundant number, since it is smaller than the sum of its proper divisors (2304540).

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

840420 is a wasteful number, since it uses less digits than its factorization.

840420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74 (or 69 counting only the distinct ones).

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

The square root of 840420 is about 916.7442391420. The cubic root of 840420 is about 94.3696026327.

Adding to 840420 its reverse (24048), we get a palindrome (864468).

The spelling of 840420 in words is "eight hundred forty thousand, four hundred twenty".