256381931520 has 1248 divisors, whose sum is σ = 1066479208704. Its totient is φ = 56151244800.

The previous prime is 256381931441. The next prime is 256381931551. The reversal of 256381931520 is 25139183652.

256381931520 is a `hidden beast` number, since 2 + 5 + 6 + 38 + 1 + 93 + 1 + 520 = 666.

It is a tau number, because it is divible by the number of its divisors (1248).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1871400892 + ... + 1871401028.

It is an arithmetic number, because the mean of its divisors is an integer number (854550648).

Almost surely, 2^256381931520 is an apocalyptic number.

256381931520 is a gapful number since it is divisible by the number (20) 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 256381931520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (533239604352).

256381931520 is an abundant number, since it is smaller than the sum of its proper divisors (810097277184).

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

256381931520 is a wasteful number, since it uses less digits than its factorization.

256381931520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267 (or 242 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 45.

The spelling of 256381931520 in words is "two hundred fifty-six billion, three hundred eighty-one million, nine hundred thirty-one thousand, five hundred twenty".