840781 has 4 divisors (see below), whose sum is σ = 843552. Its totient is φ = 838012.

The previous prime is 840767. The next prime is 840817. The reversal of 840781 is 187048.

840781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 840781 - 2⁹ = 840269 is a prime.

It is a super-2 number, since 2×840781² = 1413825379922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (840761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 865 + ... + 1558.

It is an arithmetic number, because the mean of its divisors is an integer number (210888).

2⁸⁴⁰⁷⁸¹ is an apocalyptic number.

It is an amenable number.

840781 is a deficient number, since it is larger than the sum of its proper divisors (2771).

840781 is a wasteful number, since it uses less digits than its factorization.

840781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2770.

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 840781 is about 916.9411104319. The cubic root of 840781 is about 94.3831127625.

The spelling of 840781 in words is "eight hundred forty thousand, seven hundred eighty-one".