405540 has 48 divisors (see below), whose sum is σ = 1263360. Its totient is φ = 108000.

The previous prime is 405529. The next prime is 405541. The reversal of 405540 is 45504.

It is a happy number.

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 (405541) by changing a digit.

405540 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 15 ways as a sum of consecutive naturals, for example, 165 + ... + 915.

It is an arithmetic number, because the mean of its divisors is an integer number (26320).

2⁴⁰⁵⁵⁴⁰ 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 405540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (631680).

405540 is an abundant number, since it is smaller than the sum of its proper divisors (857820).

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

405540 is a wasteful number, since it uses less digits than its factorization.

405540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769 (or 761 counting only the distinct ones).

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

The square root of 405540 is about 636.8202258095. The cubic root of 405540 is about 74.0192304538.

It can be divided in two parts, 4055 and 40, that added together give a triangular number (4095 = T₉₀).

The spelling of 405540 in words is "four hundred five thousand, five hundred forty".