256555815 has 16 divisors (see below), whose sum is σ = 410726400. Its totient is φ = 136750752.

The previous prime is 256555801. The next prime is 256555829. The reversal of 256555815 is 518555652.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (256555801) and next prime (256555829).

It is not a de Polignac number, because 256555815 - 2¹¹ = 256553767 is a prime.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 29766 + ... + 37404.

It is an arithmetic number, because the mean of its divisors is an integer number (25670400).

Almost surely, 2^256555815 is an apocalyptic number.

256555815 is a deficient number, since it is larger than the sum of its proper divisors (154170585).

256555815 is a wasteful number, since it uses less digits than its factorization.

256555815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9886.

The product of its digits is 300000, while the sum is 42.

The square root of 256555815 is about 16017.3598011657. The cubic root of 256555815 is about 635.4196205518.

The spelling of 256555815 in words is "two hundred fifty-six million, five hundred fifty-five thousand, eight hundred fifteen".