840557 has 2 divisors, whose sum is σ = 840558. Its totient is φ = 840556.

The previous prime is 840547. The next prime is 840571. The reversal of 840557 is 755048.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 749956 + 90601 = 866^2 + 301^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-840557 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420278 + 420279.

It is an arithmetic number, because the mean of its divisors is an integer number (420279).

2⁸⁴⁰⁵⁵⁷ is an apocalyptic number.

It is an amenable number.

840557 is a deficient number, since it is larger than the sum of its proper divisors (1).

840557 is an equidigital number, since it uses as much as digits as its factorization.

840557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5600, while the sum is 29.

The square root of 840557 is about 916.8189570466. The cubic root of 840557 is about 94.3747302011.

The spelling of 840557 in words is "eight hundred forty thousand, five hundred fifty-seven".