256647864 has 128 divisors (see below), whose sum is σ = 726485760. Its totient is φ = 74880000.

The previous prime is 256647863. The next prime is 256647887. The reversal of 256647864 is 468746652.

256647864 = T₂₅₇ + T₂₅₈ + ... + T₁₁₅₈.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256647863) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 1417854 + ... + 1418034.

It is an arithmetic number, because the mean of its divisors is an integer number (5675670).

Almost surely, 2^256647864 is an apocalyptic number.

256647864 is a gapful number since it is divisible by the number (24) 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 256647864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (363242880).

256647864 is an abundant number, since it is smaller than the sum of its proper divisors (469837896).

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

256647864 is a wasteful number, since it uses less digits than its factorization.

256647864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 373 (or 369 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 48.

The square root of 256647864 is about 16020.2329571077. The cubic root of 256647864 is about 635.4956049881.

The spelling of 256647864 in words is "two hundred fifty-six million, six hundred forty-seven thousand, eight hundred sixty-four".