256761521568 has 672 divisors, whose sum is σ = 837677998080. Its totient is φ = 77167157760.

The previous prime is 256761521563. The next prime is 256761521573. The reversal of 256761521568 is 865125167652.

256761521568 is a `hidden beast` number, since 2 + 5 + 6 + 7 + 61 + 521 + 56 + 8 = 666.

256761521568 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (256761521563) and next prime (256761521573).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (256761521563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 715212973 + ... + 715213331.

It is an arithmetic number, because the mean of its divisors is an integer number (1246544640).

Almost surely, 2^256761521568 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256761521568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (418838999040).

256761521568 is an abundant number, since it is smaller than the sum of its proper divisors (580916476512).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256761521568 is a wasteful number, since it uses less digits than its factorization.

256761521568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 484 (or 461 counting only the distinct ones).

The product of its digits is 6048000, while the sum is 54.

The spelling of 256761521568 in words is "two hundred fifty-six billion, seven hundred sixty-one million, five hundred twenty-one thousand, five hundred sixty-eight".