399985 has 4 divisors (see below), whose sum is σ = 479988. Its totient is φ = 319984.

The previous prime is 399983. The next prime is 399989. The reversal of 399985 is 589993.

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 85264 + 314721 = 292^2 + 561^2 .

It is a cyclic number.

It is not a de Polignac number, because 399985 - 2¹ = 399983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399983) 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, 39994 + ... + 40003.

It is an arithmetic number, because the mean of its divisors is an integer number (119997).

2³⁹⁹⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

399985 is a deficient number, since it is larger than the sum of its proper divisors (80003).

399985 is an equidigital number, since it uses as much as digits as its factorization.

399985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80002.

The product of its digits is 87480, while the sum is 43.

The square root of 399985 is about 632.4436733813. The cubic root of 399985 is about 73.6797089534.

The spelling of 399985 in words is "three hundred ninety-nine thousand, nine hundred eighty-five".