840400 has 60 divisors (see below), whose sum is σ = 2214144. Its totient is φ = 304000.

The previous prime is 840353. The next prime is 840439. The reversal of 840400 is 4048.

840400 is nontrivially palindromic in base 7.

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

It is a congruent number.

It is an unprimeable number.

840400 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 11 ways as a sum of consecutive naturals, for example, 4305 + ... + 4495.

2⁸⁴⁰⁴⁰⁰ is an apocalyptic number.

840400 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 840400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1107072).

840400 is an abundant number, since it is smaller than the sum of its proper divisors (1373744).

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

840400 is a wasteful number, since it uses less digits than its factorization.

840400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220 (or 209 counting only the distinct ones).

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

The square root of 840400 is about 916.7333309093. The cubic root of 840400 is about 94.3688540360.

840400 divided by its sum of digits (16) gives a palindrome (52525).

Adding to 840400 its reverse (4048), we get a palindrome (844448).

The spelling of 840400 in words is "eight hundred forty thousand, four hundred".