399409 has 2 divisors, whose sum is σ = 399410. Its totient is φ = 399408.

The previous prime is 399403. The next prime is 399433. The reversal of 399409 is 904993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216225 + 183184 = 465^2 + 428^2 .

It is a cyclic number.

It is not a de Polignac number, because 399409 - 2³ = 399401 is a prime.

It is not a weakly prime, because it can be changed into another prime (399401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199704 + 199705.

It is an arithmetic number, because the mean of its divisors is an integer number (199705).

2³⁹⁹⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

399409 is a deficient number, since it is larger than the sum of its proper divisors (1).

399409 is an equidigital number, since it uses as much as digits as its factorization.

399409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8748, while the sum is 34.

The square root of 399409 is about 631.9881328000. The cubic root of 399409 is about 73.6443243762.

It can be divided in two parts, 399 and 409, that added together give a palindrome (808).

The spelling of 399409 in words is "three hundred ninety-nine thousand, four hundred nine".