840257 has 4 divisors (see below), whose sum is σ = 916656. Its totient is φ = 763860.

The previous prime is 840253. The next prime is 840269. The reversal of 840257 is 752048.

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 840257 - 2² = 840253 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 840257.

It is not an unprimeable number, because it can be changed into a prime (840253) 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, 38183 + ... + 38204.

It is an arithmetic number, because the mean of its divisors is an integer number (229164).

2⁸⁴⁰²⁵⁷ is an apocalyptic number.

It is an amenable number.

840257 is a deficient number, since it is larger than the sum of its proper divisors (76399).

840257 is a wasteful number, since it uses less digits than its factorization.

840257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76398.

The product of its (nonzero) digits is 2240, while the sum is 26.

The square root of 840257 is about 916.6553332633. The cubic root of 840257 is about 94.3635012232.

Subtracting from 840257 its reverse (752048), we obtain a square (88209 = 297²).

The spelling of 840257 in words is "eight hundred forty thousand, two hundred fifty-seven".