6404399 has 4 divisors (see below), whose sum is σ = 6412536. Its totient is φ = 6396264.

The previous prime is 6404381. The next prime is 6404401. The reversal of 6404399 is 9934046.

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: 9934046 = 2 ⋅4967023.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6404399 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 (6404369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2744 + ... + 4509.

It is an arithmetic number, because the mean of its divisors is an integer number (1603134).

Almost surely, 2^6404399 is an apocalyptic number.

6404399 is a deficient number, since it is larger than the sum of its proper divisors (8137).

6404399 is an equidigital number, since it uses as much as digits as its factorization.

6404399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8136.

The product of its (nonzero) digits is 23328, while the sum is 35.

The square root of 6404399 is about 2530.6914075011. The cubic root of 6404399 is about 185.7060818298.

The spelling of 6404399 in words is "six million, four hundred four thousand, three hundred ninety-nine".