840640 has 56 divisors (see below), whose sum is σ = 2084832. Its totient is φ = 322560.

The previous prime is 840611. The next prime is 840643. The reversal of 840640 is 46048.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (840643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11805 + ... + 11875.

2⁸⁴⁰⁶⁴⁰ is an apocalyptic number.

840640 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 840640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1042416).

840640 is an abundant number, since it is smaller than the sum of its proper divisors (1244192).

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

840640 is a wasteful number, since it uses less digits than its factorization.

840640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125 (or 115 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 840640 is about 916.8642211364. The cubic root of 840640 is about 94.3778364132.

Adding to 840640 its reverse (46048), we get a palindrome (886688).

The spelling of 840640 in words is "eight hundred forty thousand, six hundred forty".