256411861 has 2 divisors, whose sum is σ = 256411862. Its totient is φ = 256411860.

The previous prime is 256411807. The next prime is 256411871. The reversal of 256411861 is 168114652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 238084900 + 18326961 = 15430^2 + 4281^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256411861 is a prime.

It is a super-2 number, since 2×256411861² = 131494084922966642, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256411871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128205930 + 128205931.

It is an arithmetic number, because the mean of its divisors is an integer number (128205931).

Almost surely, 2^256411861 is an apocalyptic number.

It is an amenable number.

256411861 is a deficient number, since it is larger than the sum of its proper divisors (1).

256411861 is an equidigital number, since it uses as much as digits as its factorization.

256411861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 34.

The square root of 256411861 is about 16012.8654837290. The cubic root of 256411861 is about 635.3007532277.

The spelling of 256411861 in words is "two hundred fifty-six million, four hundred eleven thousand, eight hundred sixty-one".