6440256 has 56 divisors (see below), whose sum is σ = 18938240. Its totient is φ = 2146176.

The previous prime is 6440249. The next prime is 6440303. The reversal of 6440256 is 6520446.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 136 + ... + 3591.

Almost surely, 2^6440256 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6440256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9469120).

6440256 is an abundant number, since it is smaller than the sum of its proper divisors (12497984).

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

6440256 is a wasteful number, since it uses less digits than its factorization.

6440256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3748 (or 3732 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 6440256 is about 2537.7659466547. The cubic root of 6440256 is about 186.0520145892.

The spelling of 6440256 in words is "six million, four hundred forty thousand, two hundred fifty-six".