256266509 has 4 divisors (see below), whose sum is σ = 269754240. Its totient is φ = 242778780.

The previous prime is 256266503. The next prime is 256266539. The reversal of 256266509 is 905662652.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 256266509 - 2²⁴ = 239489293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256266503) 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 in 3 ways as a sum of consecutive naturals, for example, 6743837 + ... + 6743874.

It is an arithmetic number, because the mean of its divisors is an integer number (67438560).

Almost surely, 2^256266509 is an apocalyptic number.

It is an amenable number.

256266509 is a deficient number, since it is larger than the sum of its proper divisors (13487731).

256266509 is a wasteful number, since it uses less digits than its factorization.

256266509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13487730.

The product of its (nonzero) digits is 194400, while the sum is 41.

The square root of 256266509 is about 16008.3262398041. The cubic root of 256266509 is about 635.1806863831.

The spelling of 256266509 in words is "two hundred fifty-six million, two hundred sixty-six thousand, five hundred nine".