256587409 has 16 divisors (see below), whose sum is σ = 293282640. Its totient is φ = 222382080.

The previous prime is 256587361. The next prime is 256587413. The reversal of 256587409 is 904785652.

It can be written as a sum of positive squares in 8 ways, for example, as 7579009 + 249008400 = 2753^2 + 15780^2 .

It is a cyclic number.

It is not a de Polignac number, because 256587409 - 2⁷ = 256587281 is a prime.

It is not an unprimeable number, because it can be changed into a prime (256587439) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111349 + ... + 113629.

It is an arithmetic number, because the mean of its divisors is an integer number (18330165).

Almost surely, 2^256587409 is an apocalyptic number.

It is an amenable number.

256587409 is a deficient number, since it is larger than the sum of its proper divisors (36695231).

256587409 is a wasteful number, since it uses less digits than its factorization.

256587409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2820.

The product of its (nonzero) digits is 604800, while the sum is 46.

The square root of 256587409 is about 16018.3460132437. The cubic root of 256587409 is about 635.4457027560.

The spelling of 256587409 in words is "two hundred fifty-six million, five hundred eighty-seven thousand, four hundred nine".