408640 has 28 divisors (see below), whose sum is σ = 973836. Its totient is φ = 163328.

The previous prime is 408637. The next prime is 408643. The reversal of 408640 is 46804.

It is an interprime number because it is at equal distance from previous prime (408637) and next prime (408643).

It can be written as a sum of positive squares in 2 ways, for example, as 207936 + 200704 = 456^2 + 448^2 .

It is not an unprimeable number, because it can be changed into a prime (408643) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 319 + ... + 958.

2⁴⁰⁸⁶⁴⁰ is an apocalyptic number.

408640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

408640 is the 320-th decagonal number.

It is an amenable number.

408640 is an abundant number, since it is smaller than the sum of its proper divisors (565196).

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

408640 is a wasteful number, since it uses less digits than its factorization.

408640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1294 (or 1284 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 408640 is about 639.2495600311. The cubic root of 408640 is about 74.2073560903.

The spelling of 408640 in words is "four hundred eight thousand, six hundred forty".