256681049769 has 45 divisors (see below), whose sum is σ = 393303804949. Its totient is φ = 166825431360.

The previous prime is 256681049761. The next prime is 256681049783. The reversal of 256681049769 is 967940186652.

The square root of 256681049769 is 506637.

It is a perfect power (a square), and thus also a powerful number.

256681049769 is a `hidden beast` number, since 2 + 5 + 6 + 6 + 81 + 0 + 497 + 69 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 3281571225 + 253399478544 = 57285^2 + 503388^2 .

It is not a de Polignac number, because 256681049769 - 2³ = 256681049761 is a prime.

It is a super-2 number, since 2×256681049769² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256681049761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 186948367 + ... + 186949739.

Almost surely, 2^256681049769 is an apocalyptic number.

256681049769 is the 506637-th square number.

256681049769 is the 253319-th centered octagonal number.

It is an amenable number.

256681049769 is a deficient number, since it is larger than the sum of its proper divisors (136622755180).

256681049769 is an frugal number, since it uses more digits than its factorization.

256681049769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2840 (or 1417 counting only the distinct ones).

The product of its (nonzero) digits is 39191040, while the sum is 63.

The spelling of 256681049769 in words is "two hundred fifty-six billion, six hundred eighty-one million, forty-nine thousand, seven hundred sixty-nine".