6406399 has 4 divisors (see below), whose sum is σ = 6783264. Its totient is φ = 6029536.

The previous prime is 6406381. The next prime is 6406427. The reversal of 6406399 is 9936046.

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 6406399 - 2¹³ = 6398207 is a prime.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6406369) 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, 188407 + ... + 188440.

It is an arithmetic number, because the mean of its divisors is an integer number (1695816).

Almost surely, 2^6406399 is an apocalyptic number.

6406399 is a deficient number, since it is larger than the sum of its proper divisors (376865).

6406399 is a wasteful number, since it uses less digits than its factorization.

6406399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376864.

The product of its (nonzero) digits is 34992, while the sum is 37.

The square root of 6406399 is about 2531.0865255854. The cubic root of 6406399 is about 185.7254109143.

The spelling of 6406399 in words is "six million, four hundred six thousand, three hundred ninety-nine".