256984821 has 6 divisors (see below), whose sum is σ = 371200310. Its totient is φ = 171323208.

The previous prime is 256984817. The next prime is 256984829. The reversal of 256984821 is 128489652.

256984821 is a `hidden beast` number, since 2 + 569 + 8 + 4 + 82 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 203490225 + 53494596 = 14265^2 + 7314^2 .

It is not a de Polignac number, because 256984821 - 2² = 256984817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256984829) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14276926 + ... + 14276943.

Almost surely, 2^256984821 is an apocalyptic number.

It is an amenable number.

256984821 is a deficient number, since it is larger than the sum of its proper divisors (114215489).

256984821 is a wasteful number, since it uses less digits than its factorization.

256984821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28553875 (or 28553872 counting only the distinct ones).

The product of its digits is 276480, while the sum is 45.

The square root of 256984821 is about 16030.7461148881. The cubic root of 256984821 is about 635.7736007393.

The spelling of 256984821 in words is "two hundred fifty-six million, nine hundred eighty-four thousand, eight hundred twenty-one".