399959999 has 4 divisors (see below), whose sum is σ = 400155936. Its totient is φ = 399764064.

The previous prime is 399959983. The next prime is 399960007. The reversal of 399959999 is 999959993.

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 399959999 - 2⁴ = 399959983 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 (399959929) 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, 94874 + ... + 98999.

It is an arithmetic number, because the mean of its divisors is an integer number (100038984).

Almost surely, 2^399959999 is an apocalyptic number.

399959999 is a deficient number, since it is larger than the sum of its proper divisors (195937).

399959999 is a wasteful number, since it uses less digits than its factorization.

399959999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195936.

The product of its digits is 71744535, while the sum is 71.

The square root of 399959999 is about 19998.9999499975. Note that the first 4 decimals coincide. The cubic root of 399959999 is about 736.7817380853.

It can be divided in two parts, 39995 and 9999, that added together give a palindrome (49994).

The spelling of 399959999 in words is "three hundred ninety-nine million, nine hundred fifty-nine thousand, nine hundred ninety-nine".