256561049 has 2 divisors, whose sum is σ = 256561050. Its totient is φ = 256561048.

The previous prime is 256561013. The next prime is 256561073. The reversal of 256561049 is 940165652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 252015625 + 4545424 = 15875^2 + 2132^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256561049 is a prime.

It is not a weakly prime, because it can be changed into another prime (256561099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128280524 + 128280525.

It is an arithmetic number, because the mean of its divisors is an integer number (128280525).

Almost surely, 2^256561049 is an apocalyptic number.

It is an amenable number.

256561049 is a deficient number, since it is larger than the sum of its proper divisors (1).

256561049 is an equidigital number, since it uses as much as digits as its factorization.

256561049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64800, while the sum is 38.

The square root of 256561049 is about 16017.5231855615. The cubic root of 256561049 is about 635.4239415916.

The spelling of 256561049 in words is "two hundred fifty-six million, five hundred sixty-one thousand, forty-nine".