256644673808544 has 720 divisors, whose sum is σ = 897408120379680. Its totient is φ = 69376667028480.

The previous prime is 256644673808543. The next prime is 256644673808561. The reversal of 256644673808544 is 445808376446652.

256644673808544 is a `hidden beast` number, since 2 + 5 + 6 + 6 + 4 + 4 + 6 + 73 + 8 + 0 + 8 + 544 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (256644673808543) by changing a digit.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 10339807654 + ... + 10339832474.

It is an arithmetic number, because the mean of its divisors is an integer number (1246400167194).

Almost surely, 2^{256644673808544} is an apocalyptic number.

256644673808544 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 256644673808544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (448704060189840).

256644673808544 is an abundant number, since it is smaller than the sum of its proper divisors (640763446571136).

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

256644673808544 is a wasteful number, since it uses less digits than its factorization.

256644673808544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25671 (or 25639 counting only the distinct ones).

The product of its (nonzero) digits is 3715891200, while the sum is 72.

The spelling of 256644673808544 in words is "two hundred fifty-six trillion, six hundred forty-four billion, six hundred seventy-three million, eight hundred eight thousand, five hundred forty-four".