399998 has 4 divisors (see below), whose sum is σ = 600000. Its totient is φ = 199998.

The previous prime is 399989. The next prime is 400009. The reversal of 399998 is 899993.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 899993 = 53 ⋅16981.

It is a congruent number.

It is an unprimeable number.

399998 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99998 + ... + 100001.

It is an arithmetic number, because the mean of its divisors is an integer number (150000).

2³⁹⁹⁹⁹⁸ is an apocalyptic number.

399998 is a deficient number, since it is larger than the sum of its proper divisors (200002).

399998 is a wasteful number, since it uses less digits than its factorization.

399998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200001.

The product of its digits is 157464, while the sum is 47.

The square root of 399998 is about 632.4539508929. The cubic root of 399998 is about 73.6805071716.

It can be divided in two parts, 3 and 99998, that added together give a palindrome (100001).

The spelling of 399998 in words is "three hundred ninety-nine thousand, nine hundred ninety-eight".