840657 has 4 divisors (see below), whose sum is σ = 1120880. Its totient is φ = 560436.

The previous prime is 840643. The next prime is 840661. The reversal of 840657 is 756048.

It is a happy number.

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 not a de Polignac number, because 840657 - 2¹⁰ = 839633 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (840457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 140107 + ... + 140112.

It is an arithmetic number, because the mean of its divisors is an integer number (280220).

2⁸⁴⁰⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

840657 is a deficient number, since it is larger than the sum of its proper divisors (280223).

840657 is a wasteful number, since it uses less digits than its factorization.

840657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280222.

The product of its (nonzero) digits is 6720, while the sum is 30.

The square root of 840657 is about 916.8734918188. The cubic root of 840657 is about 94.3784726000.

The spelling of 840657 in words is "eight hundred forty thousand, six hundred fifty-seven".