399343993 has 4 divisors (see below), whose sum is σ = 400765428. Its totient is φ = 397922560.

The previous prime is 399343961. The next prime is 399344039.

It is a happy number.

399343993 is nontrivially palindromic in base 10.

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 360506169 + 38837824 = 18987^2 + 6232^2 .

It is a cyclic number.

It is not a de Polignac number, because 399343993 - 2⁵ = 399343961 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 399343993.

It is not an unprimeable number, because it can be changed into a prime (399343933) 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, 710296 + ... + 710857.

It is an arithmetic number, because the mean of its divisors is an integer number (100191357).

Almost surely, 2^399343993 is an apocalyptic number.

It is an amenable number.

399343993 is a deficient number, since it is larger than the sum of its proper divisors (1421435).

399343993 is a wasteful number, since it uses less digits than its factorization.

399343993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1421434.

The product of its digits is 2125764, while the sum is 52.

The square root of 399343993 is about 19983.5930953370. The cubic root of 399343993 is about 736.4032875902.

The spelling of 399343993 in words is "three hundred ninety-nine million, three hundred forty-three thousand, nine hundred ninety-three".