256781782551168 has 512 divisors, whose sum is σ = 919085202316800. Its totient is φ = 68899417620480.

The previous prime is 256781782551163. The next prime is 256781782551169. The reversal of 256781782551168 is 861155287187652.

256781782551168 is a `hidden beast` number, since 2 + 5 + 6 + 7 + 8 + 1 + 7 + 8 + 2 + 551 + 1 + 68 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 256781782551096 and 256781782551105.

It is not an unprimeable number, because it can be changed into a prime (256781782551163) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 187264528 + ... + 188630768.

It is an arithmetic number, because the mean of its divisors is an integer number (1795088285775).

Almost surely, 2^{256781782551168} is an apocalyptic number.

256781782551168 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256781782551168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (459542601158400).

256781782551168 is an abundant number, since it is smaller than the sum of its proper divisors (662303419765632).

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

256781782551168 is a wasteful number, since it uses less digits than its factorization.

256781782551168 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1366745 (or 1366727 counting only the distinct ones).

The product of its digits is 451584000, while the sum is 72.

The spelling of 256781782551168 in words is "two hundred fifty-six trillion, seven hundred eighty-one billion, seven hundred eighty-two million, five hundred fifty-one thousand, one hundred sixty-eight".