6405440 has 56 divisors (see below), whose sum is σ = 15694152. Its totient is φ = 2488320.

The previous prime is 6405397. The next prime is 6405457. The reversal of 6405440 is 445046.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1459264 + 4946176 = 1208^2 + 2224^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11570 + ... + 12110.

Almost surely, 2^6405440 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 6405440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7847076).

6405440 is an abundant number, since it is smaller than the sum of its proper divisors (9288712).

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

6405440 is a wasteful number, since it uses less digits than its factorization.

6405440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 595 (or 585 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 23.

The square root of 6405440 is about 2530.8970741616. The cubic root of 6405440 is about 185.7161431203.

The spelling of 6405440 in words is "six million, four hundred five thousand, four hundred forty".