256437640 has 32 divisors (see below), whose sum is σ = 589265280. Its totient is φ = 100391872.

The previous prime is 256437619. The next prime is 256437641. The reversal of 256437640 is 46734652.

256437640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 256437640.

It is not an unprimeable number, because it can be changed into a prime (256437641) 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, 66322 + ... + 70081.

It is an arithmetic number, because the mean of its divisors is an integer number (18414540).

Almost surely, 2^256437640 is an apocalyptic number.

256437640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256437640 is an abundant number, since it is smaller than the sum of its proper divisors (332827640).

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

256437640 is a wasteful number, since it uses less digits than its factorization.

256437640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 136461 (or 136457 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 37.

The square root of 256437640 is about 16013.6704099966. The cubic root of 256437640 is about 635.3220430246.

It can be divided in two parts, 2564 and 37640, that added together give a palindrome (40204).

The spelling of 256437640 in words is "two hundred fifty-six million, four hundred thirty-seven thousand, six hundred forty".