257840 has 40 divisors (see below), whose sum is σ = 656208. Its totient is φ = 93440.

The previous prime is 257837. The next prime is 257857. The reversal of 257840 is 48752.

257840 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 734 + ... + 1026.

2²⁵⁷⁸⁴⁰ is an apocalyptic number.

257840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 257840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (328104).

257840 is an abundant number, since it is smaller than the sum of its proper divisors (398368).

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

257840 is a wasteful number, since it uses less digits than its factorization.

257840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317 (or 311 counting only the distinct ones).

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

The square root of 257840 is about 507.7794796957. The cubic root of 257840 is about 63.6478049929.

The spelling of 257840 in words is "two hundred fifty-seven thousand, eight hundred forty".