256821290 has 48 divisors (see below), whose sum is σ = 534915360. Its totient is φ = 88466400.

The previous prime is 256821287. The next prime is 256821307. The reversal of 256821290 is 92128652.

It is a happy number.

256821290 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 256821290.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17405 + ... + 28575.

It is an arithmetic number, because the mean of its divisors is an integer number (11144070).

Almost surely, 2^256821290 is an apocalyptic number.

256821290 is an abundant number, since it is smaller than the sum of its proper divisors (278094070).

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

256821290 is a wasteful number, since it uses less digits than its factorization.

256821290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11219 (or 11208 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 35.

The square root of 256821290 is about 16025.6447608201. The cubic root of 256821290 is about 635.6387150116.

The spelling of 256821290 in words is "two hundred fifty-six million, eight hundred twenty-one thousand, two hundred ninety".