256865440 has 48 divisors (see below), whose sum is σ = 653530248. Its totient is φ = 94841856.

The previous prime is 256865431. The next prime is 256865447. The reversal of 256865440 is 44568652.

It can be written as a sum of positive squares in 4 ways, for example, as 125350416 + 131515024 = 11196^2 + 11468^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 256865393 and 256865402.

It is not an unprimeable number, because it can be changed into a prime (256865447) 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, 59667 + ... + 63826.

Almost surely, 2^256865440 is an apocalyptic number.

256865440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256865440 is an abundant number, since it is smaller than the sum of its proper divisors (396664808).

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

256865440 is a wasteful number, since it uses less digits than its factorization.

256865440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123521 (or 123513 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 40.

The square root of 256865440 is about 16027.0221813037. The cubic root of 256865440 is about 635.6751370196.

The spelling of 256865440 in words is "two hundred fifty-six million, eight hundred sixty-five thousand, four hundred forty".