256844981 has 2 divisors, whose sum is σ = 256844982. Its totient is φ = 256844980.

The previous prime is 256844971. The next prime is 256845031. The reversal of 256844981 is 189448652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 208542481 + 48302500 = 14441^2 + 6950^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256844981 is a prime.

It is a super-2 number, since 2×256844981² = 131938688529780722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256844921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128422490 + 128422491.

It is an arithmetic number, because the mean of its divisors is an integer number (128422491).

Almost surely, 2^256844981 is an apocalyptic number.

It is an amenable number.

256844981 is a deficient number, since it is larger than the sum of its proper divisors (1).

256844981 is an equidigital number, since it uses as much as digits as its factorization.

256844981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 552960, while the sum is 47.

The square root of 256844981 is about 16026.3839028023. The cubic root of 256844981 is about 635.6582596708.

The spelling of 256844981 in words is "two hundred fifty-six million, eight hundred forty-four thousand, nine hundred eighty-one".