256779515 has 16 divisors (see below), whose sum is σ = 318741696. Its totient is φ = 198451200.

The previous prime is 256779493. The next prime is 256779529. The reversal of 256779515 is 515977652.

It is not a de Polignac number, because 256779515 - 2¹⁰ = 256778491 is a prime.

It is a super-3 number, since 3×256779515³ (a number of 26 digits) contains 333 as substring.

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 256779515.

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, 15035 + ... + 27195.

It is an arithmetic number, because the mean of its divisors is an integer number (19921356).

Almost surely, 2^256779515 is an apocalyptic number.

256779515 is a deficient number, since it is larger than the sum of its proper divisors (61962181).

256779515 is a wasteful number, since it uses less digits than its factorization.

256779515 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12310.

The product of its digits is 661500, while the sum is 47.

The square root of 256779515 is about 16024.3413281170. The cubic root of 256779515 is about 635.6042484412.

The spelling of 256779515 in words is "two hundred fifty-six million, seven hundred seventy-nine thousand, five hundred fifteen".