404840 has 32 divisors (see below), whose sum is σ = 945000. Its totient is φ = 155904.

The previous prime is 404837. The next prime is 404843. The reversal of 404840 is 48404.

It is an interprime number because it is at equal distance from previous prime (404837) and next prime (404843).

It can be written as a sum of positive squares in 4 ways, for example, as 362404 + 42436 = 602^2 + 206^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a plaindrome in base 13.

It is a nialpdrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (404843) 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, 986 + ... + 1334.

2⁴⁰⁴⁸⁴⁰ is an apocalyptic number.

404840 is a gapful number since it is divisible by the number (40) 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 404840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (472500).

404840 is an abundant number, since it is smaller than the sum of its proper divisors (540160).

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

404840 is a wasteful number, since it uses less digits than its factorization.

404840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389 (or 385 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 20.

The square root of 404840 is about 636.2703827776. The cubic root of 404840 is about 73.9766178865.

It can be divided in two parts, 40 and 4840, that multiplied together give a square (193600 = 440²).

The spelling of 404840 in words is "four hundred four thousand, eight hundred forty".