399999 has 8 divisors (see below), whose sum is σ = 537472. Its totient is φ = 264600.

The previous prime is 399989. The next prime is 400009. The reversal of 399999 is 999993.

It is an interprime number because it is at equal distance from previous prime (399989) and next prime (400009).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 399999 - 2⁴ = 399983 is a prime.

It is a Duffinian number.

399999 is a modest number, since divided by 999 gives 399 as remainder.

It is a plaindrome in base 10.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 399999.

It is not an unprimeable number, because it can be changed into a prime (399979) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12 + ... + 894.

It is an arithmetic number, because the mean of its divisors is an integer number (67184).

2³⁹⁹⁹⁹⁹ is an apocalyptic number.

399999 is a deficient number, since it is larger than the sum of its proper divisors (137473).

399999 is a wasteful number, since it uses less digits than its factorization.

399999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1037.

The product of its digits is 177147, while the sum is 48.

The square root of 399999 is about 632.4547414638. The cubic root of 399999 is about 73.6805685722.

The spelling of 399999 in words is "three hundred ninety-nine thousand, nine hundred ninety-nine".