256863509 has 8 divisors (see below), whose sum is σ = 301492608. Its totient is φ = 214218000.

The previous prime is 256863499. The next prime is 256863539. The reversal of 256863509 is 905368652.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 256863509 - 2¹⁶ = 256797973 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 256863509.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256863539) 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 in 7 ways as a sum of consecutive naturals, for example, 495617 + ... + 496134.

It is an arithmetic number, because the mean of its divisors is an integer number (37686576).

Almost surely, 2^256863509 is an apocalyptic number.

It is an amenable number.

256863509 is a deficient number, since it is larger than the sum of its proper divisors (44629099).

256863509 is an equidigital number, since it uses as much as digits as its factorization.

256863509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 991795.

The product of its (nonzero) digits is 388800, while the sum is 44.

The square root of 256863509 is about 16026.9619391824. The cubic root of 256863509 is about 635.6735441081.

The spelling of 256863509 in words is "two hundred fifty-six million, eight hundred sixty-three thousand, five hundred nine".