256776521 has 4 divisors (see below), whose sum is σ = 262748112. Its totient is φ = 250804932.

The previous prime is 256776491. The next prime is 256776523. The reversal of 256776521 is 125677652.

256776521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 256776521 - 2¹⁴ = 256760137 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (256776523) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2985731 + ... + 2985816.

It is an arithmetic number, because the mean of its divisors is an integer number (65687028).

Almost surely, 2^256776521 is an apocalyptic number.

It is an amenable number.

256776521 is a deficient number, since it is larger than the sum of its proper divisors (5971591).

256776521 is an equidigital number, since it uses as much as digits as its factorization.

256776521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5971590.

The product of its digits is 176400, while the sum is 41.

The square root of 256776521 is about 16024.2479074682. The cubic root of 256776521 is about 635.6017780903.

The spelling of 256776521 in words is "two hundred fifty-six million, seven hundred seventy-six thousand, five hundred twenty-one".