399839999 has 4 divisors (see below), whose sum is σ = 430596936. Its totient is φ = 369083064.

The previous prime is 399839989. The next prime is 399840011. The reversal of 399839999 is 999938993.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 399839999 - 2²⁴ = 383062783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (399839989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15378449 + ... + 15378474.

It is an arithmetic number, because the mean of its divisors is an integer number (107649234).

Almost surely, 2^399839999 is an apocalyptic number.

399839999 is a deficient number, since it is larger than the sum of its proper divisors (30756937).

399839999 is a wasteful number, since it uses less digits than its factorization.

399839999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30756936.

The product of its digits is 38263752, while the sum is 68.

The square root of 399839999 is about 19995.9995749150. Note that the first 3 decimals coincide. The cubic root of 399839999 is about 736.7080451723.

The spelling of 399839999 in words is "three hundred ninety-nine million, eight hundred thirty-nine thousand, nine hundred ninety-nine".