840256 has 28 divisors (see below), whose sum is σ = 1757680. Its totient is φ = 397440.

The previous prime is 840253. The next prime is 840269. The reversal of 840256 is 652048.

It is a self number, because there is not a number n which added to its sum of digits gives 840256.

It is not an unprimeable number, because it can be changed into a prime (840253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 871 + ... + 1561.

2⁸⁴⁰²⁵⁶ 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 840256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (878840).

840256 is an abundant number, since it is smaller than the sum of its proper divisors (917424).

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

840256 is a wasteful number, since it uses less digits than its factorization.

840256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722 (or 712 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 840256 is about 916.6547878018. The cubic root of 840256 is about 94.3634637888.

The spelling of 840256 in words is "eight hundred forty thousand, two hundred fifty-six".