257920 has 64 divisors (see below), whose sum is σ = 685440. Its totient is φ = 92160.

The previous prime is 257903. The next prime is 257921. The reversal of 257920 is 29752.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (257921) by changing a digit.

257920 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8305 + ... + 8335.

It is an arithmetic number, because the mean of its divisors is an integer number (10710).

2²⁵⁷⁹²⁰ is an apocalyptic number.

257920 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 257920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (342720).

257920 is an abundant number, since it is smaller than the sum of its proper divisors (427520).

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

257920 is a wasteful number, since it uses less digits than its factorization.

257920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63 (or 51 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 257920 is about 507.8582479393. The cubic root of 257920 is about 63.6543869790.

The spelling of 257920 in words is "two hundred fifty-seven thousand, nine hundred twenty".