256511005 has 4 divisors (see below), whose sum is σ = 307813212. Its totient is φ = 205208800.

The previous prime is 256510999. The next prime is 256511023. The reversal of 256511005 is 500115652.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 179720836 + 76790169 = 13406^2 + 8763^2 .

It is not a de Polignac number, because 256511005 - 2³ = 256510997 is a prime.

It is a super-2 number, since 2×256511005² = 131595791372220050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 25651096 + ... + 25651105.

It is an arithmetic number, because the mean of its divisors is an integer number (76953303).

Almost surely, 2^256511005 is an apocalyptic number.

It is an amenable number.

256511005 is a deficient number, since it is larger than the sum of its proper divisors (51302207).

256511005 is an equidigital number, since it uses as much as digits as its factorization.

256511005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51302206.

The product of its (nonzero) digits is 1500, while the sum is 25.

The square root of 256511005 is about 16015.9609452571. The cubic root of 256511005 is about 635.3826242994.

Adding to 256511005 its reverse (500115652), we get a palindrome (756626657).

The spelling of 256511005 in words is "two hundred fifty-six million, five hundred eleven thousand, five".