400040405 has 4 divisors (see below), whose sum is σ = 480048492. Its totient is φ = 320032320.

The previous prime is 400040393. The next prime is 400040419. The reversal of 400040405 is 504040004.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 133240849 + 266799556 = 11543^2 + 16334^2 .

It is not a de Polignac number, because 400040405 - 2¹⁴ = 400024021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40004036 + ... + 40004045.

It is an arithmetic number, because the mean of its divisors is an integer number (120012123).

Almost surely, 2^400040405 is an apocalyptic number.

It is an amenable number.

400040405 is a deficient number, since it is larger than the sum of its proper divisors (80008087).

400040405 is an equidigital number, since it uses as much as digits as its factorization.

400040405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80008086.

The product of its (nonzero) digits is 320, while the sum is 17.

The square root of 400040405 is about 20001.0100994925. The cubic root of 400040405 is about 736.8311077749.

Adding to 400040405 its reverse (504040004), we get a palindrome (904080409).

The spelling of 400040405 in words is "four hundred million, forty thousand, four hundred five".