256139731 has 8 divisors (see below), whose sum is σ = 271359504. Its totient is φ = 240936960.

The previous prime is 256139717. The next prime is 256139747. The reversal of 256139731 is 137931652.

256139731 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 256139731 - 2¹³ = 256131539 is a prime.

It is a super-2 number, since 2×256139731² = 131215123593504722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256139711) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40051 + ... + 46003.

It is an arithmetic number, because the mean of its divisors is an integer number (33919938).

Almost surely, 2^256139731 is an apocalyptic number.

256139731 is a deficient number, since it is larger than the sum of its proper divisors (15219773).

256139731 is a wasteful number, since it uses less digits than its factorization.

256139731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8501.

The product of its digits is 34020, while the sum is 37.

The square root of 256139731 is about 16004.3659980644. The cubic root of 256139731 is about 635.0759253666.

It can be divided in two parts, 25613 and 9731, that added together give a square (35344 = 188²).

The spelling of 256139731 in words is "two hundred fifty-six million, one hundred thirty-nine thousand, seven hundred thirty-one".