257821056 has 144 divisors (see below), whose sum is σ = 772912140. Its totient is φ = 85660416.

The previous prime is 257821027. The next prime is 257821073. The reversal of 257821056 is 650128752.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 257821056.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 839655 + ... + 839961.

Almost surely, 2^257821056 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 257821056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (386456070).

257821056 is an abundant number, since it is smaller than the sum of its proper divisors (515091084).

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

257821056 is an frugal number, since it uses more digits than its factorization.

257821056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345 (or 312 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 36.

The square root of 257821056 is about 16056.8071545996. The cubic root of 257821056 is about 636.4624617923.

The spelling of 257821056 in words is "two hundred fifty-seven million, eight hundred twenty-one thousand, fifty-six".