405640 has 16 divisors (see below), whose sum is σ = 912780. Its totient is φ = 162240.

The previous prime is 405611. The next prime is 405641. The reversal of 405640 is 46504.

It can be written as a sum of positive squares in 2 ways, for example, as 381924 + 23716 = 618^2 + 154^2 .

It is not an unprimeable number, because it can be changed into a prime (405641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5031 + ... + 5110.

2⁴⁰⁵⁶⁴⁰ is an apocalyptic number.

405640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

405640 is an abundant number, since it is smaller than the sum of its proper divisors (507140).

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

405640 is a wasteful number, since it uses less digits than its factorization.

405640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10152 (or 10148 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 405640 is about 636.8987360641. The cubic root of 405640 is about 74.0253139595.

It can be divided in two parts, 4056 and 40, that added together give a 12-th power (4096 = 2¹²).

The spelling of 405640 in words is "four hundred five thousand, six hundred forty".