256105609 has 2 divisors, whose sum is σ = 256105610. Its totient is φ = 256105608.

The previous prime is 256105571. The next prime is 256105627. The reversal of 256105609 is 906501652.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 141015625 + 115089984 = 11875^2 + 10728^2 .

It is a cyclic number.

It is not a de Polignac number, because 256105609 - 2⁷ = 256105481 is a prime.

It is a super-2 number, since 2×256105609² = 131180165922521762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (256105669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128052804 + 128052805.

It is an arithmetic number, because the mean of its divisors is an integer number (128052805).

Almost surely, 2^256105609 is an apocalyptic number.

It is an amenable number.

256105609 is a deficient number, since it is larger than the sum of its proper divisors (1).

256105609 is an equidigital number, since it uses as much as digits as its factorization.

256105609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 256105609 is about 16003.2999409497. The cubic root of 256105609 is about 635.0477232821.

The spelling of 256105609 in words is "two hundred fifty-six million, one hundred five thousand, six hundred nine".