256643478 has 144 divisors (see below), whose sum is σ = 723275280. Its totient is φ = 67604544.

The previous prime is 256643449. The next prime is 256643489. The reversal of 256643478 is 874346652.

256643478 is a `hidden beast` number, since 2 + 566 + 43 + 47 + 8 = 666.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 309168 + ... + 309996.

It is an arithmetic number, because the mean of its divisors is an integer number (5022745).

Almost surely, 2^256643478 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256643478, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (361637640).

256643478 is an abundant number, since it is smaller than the sum of its proper divisors (466631802).

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

256643478 is a wasteful number, since it uses less digits than its factorization.

256643478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 873 (or 854 counting only the distinct ones).

The product of its digits is 967680, while the sum is 45.

The square root of 256643478 is about 16020.0960671277. The cubic root of 256643478 is about 635.4919848533.

The spelling of 256643478 in words is "two hundred fifty-six million, six hundred forty-three thousand, four hundred seventy-eight".