6440399 has 8 divisors (see below), whose sum is σ = 7793568. Its totient is φ = 5195520.

The previous prime is 6440393. The next prime is 6440419. The reversal of 6440399 is 9930446.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6440399 - 2⁴ = 6440383 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 (6440393) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26942 + ... + 27179.

It is an arithmetic number, because the mean of its divisors is an integer number (974196).

Almost surely, 2^6440399 is an apocalyptic number.

6440399 is a deficient number, since it is larger than the sum of its proper divisors (1353169).

6440399 is a wasteful number, since it uses less digits than its factorization.

6440399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54145.

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

The square root of 6440399 is about 2537.7941208853. The cubic root of 6440399 is about 186.0533916173.

The spelling of 6440399 in words is "six million, four hundred forty thousand, three hundred ninety-nine".