6400440 has 96 divisors (see below), whose sum is σ = 21733920. Its totient is φ = 1630464.

The previous prime is 6400423. The next prime is 6400451. The reversal of 6400440 is 440046.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nialpdrome in base 15.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7894 + ... + 8666.

It is an arithmetic number, because the mean of its divisors is an integer number (226395).

Almost surely, 2^6400440 is an apocalyptic number.

6400440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6400440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10866960).

6400440 is an abundant number, since it is smaller than the sum of its proper divisors (15333480).

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

6400440 is a wasteful number, since it uses less digits than its factorization.

6400440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 813 (or 806 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 6400440 is about 2529.9090892757. The cubic root of 6400440 is about 185.6678080368.

Adding to 6400440 its reverse (440046), we get a palindrome (6840486).

The spelling of 6400440 in words is "six million, four hundred thousand, four hundred forty".