400409 has 2 divisors, whose sum is σ = 400410. Its totient is φ = 400408.

The previous prime is 400391. The next prime is 400417. The reversal of 400409 is 904004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 336400 + 64009 = 580^2 + 253^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400409 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 400409.

It is not a weakly prime, because it can be changed into another prime (400429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200204 + 200205.

It is an arithmetic number, because the mean of its divisors is an integer number (200205).

2⁴⁰⁰⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

400409 is a deficient number, since it is larger than the sum of its proper divisors (1).

400409 is an equidigital number, since it uses as much as digits as its factorization.

400409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 400409 is about 632.7787923121. The cubic root of 400409 is about 73.7057342331.

The spelling of 400409 in words is "four hundred thousand, four hundred nine".