256447561 has 2 divisors, whose sum is σ = 256447562. Its totient is φ = 256447560.

The previous prime is 256447553. The next prime is 256447591. The reversal of 256447561 is 165744652.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 256000000 + 447561 = 16000^2 + 669^2 .

It is a cyclic number.

It is not a de Polignac number, because 256447561 - 2³ = 256447553 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (256447591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128223780 + 128223781.

It is an arithmetic number, because the mean of its divisors is an integer number (128223781).

Almost surely, 2^256447561 is an apocalyptic number.

It is an amenable number.

256447561 is a deficient number, since it is larger than the sum of its proper divisors (1).

256447561 is an equidigital number, since it uses as much as digits as its factorization.

256447561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 201600, while the sum is 40.

The square root of 256447561 is about 16013.9801735858. The cubic root of 256447561 is about 635.3302359830.

It can be divided in two parts, 256 and 447561, that multiplied together give a square (114575616 = 10704²).

The spelling of 256447561 in words is "two hundred fifty-six million, four hundred forty-seven thousand, five hundred sixty-one".