505440 has 144 divisors (see below), whose sum is σ = 1926288. Its totient is φ = 124416.

The previous prime is 505429. The next prime is 505447. The reversal of 505440 is 44505.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (144).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (505447) by changing a digit.

505440 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 38874 + ... + 38886.

It is an arithmetic number, because the mean of its divisors is an integer number (13377).

2⁵⁰⁵⁴⁴⁰ 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 505440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (963144).

505440 is an abundant number, since it is smaller than the sum of its proper divisors (1420848).

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

505440 is a wasteful number, since it uses less digits than its factorization.

505440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43 (or 23 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 18.

The square root of 505440 is about 710.9430356927. The cubic root of 505440 is about 79.6568636557.

Adding to 505440 its reverse (44505), we get a palindrome (549945).

The spelling of 505440 in words is "five hundred five thousand, four hundred forty".