399404993 has 4 divisors (see below), whose sum is σ = 430128468. Its totient is φ = 368681520.

The previous prime is 399404989. The next prime is 399405007.

399404993 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 34480384 + 364924609 = 5872^2 + 19103^2 .

It is a cyclic number.

It is not a de Polignac number, because 399404993 - 2² = 399404989 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399404923) 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, 15361718 + ... + 15361743.

It is an arithmetic number, because the mean of its divisors is an integer number (107532117).

Almost surely, 2^399404993 is an apocalyptic number.

It is an amenable number.

399404993 is a deficient number, since it is larger than the sum of its proper divisors (30723475).

399404993 is a wasteful number, since it uses less digits than its factorization.

399404993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30723474.

The product of its (nonzero) digits is 944784, while the sum is 50.

The square root of 399404993 is about 19985.1192891111. The cubic root of 399404993 is about 736.4407810080.

The spelling of 399404993 in words is "three hundred ninety-nine million, four hundred four thousand, nine hundred ninety-three".