256381639 has 8 divisors (see below), whose sum is σ = 260402688. Its totient is φ = 252372120.

The previous prime is 256381633. The next prime is 256381673. The reversal of 256381639 is 936183652.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256381639 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 256381595 and 256381604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256381633) 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 7 ways as a sum of consecutive naturals, for example, 49134 + ... + 54100.

It is an arithmetic number, because the mean of its divisors is an integer number (32550336).

Almost surely, 2^256381639 is an apocalyptic number.

256381639 is a deficient number, since it is larger than the sum of its proper divisors (4021049).

256381639 is an equidigital number, since it uses as much as digits as its factorization.

256381639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5765.

The product of its digits is 233280, while the sum is 43.

The square root of 256381639 is about 16011.9217772259. The cubic root of 256381639 is about 635.2757923261.

The spelling of 256381639 in words is "two hundred fifty-six million, three hundred eighty-one thousand, six hundred thirty-nine".