6440993 has 4 divisors (see below), whose sum is σ = 6936468. Its totient is φ = 5945520.

The previous prime is 6440983. The next prime is 6440999. The reversal of 6440993 is 3990446.

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: 3990446 = 2 ⋅1995223.

It can be written as a sum of positive squares in 2 ways, for example, as 833569 + 5607424 = 913^2 + 2368^2 .

It is a cyclic number.

It is not a de Polignac number, because 6440993 - 2⁸ = 6440737 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6440999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 247718 + ... + 247743.

It is an arithmetic number, because the mean of its divisors is an integer number (1734117).

Almost surely, 2^6440993 is an apocalyptic number.

It is an amenable number.

6440993 is a deficient number, since it is larger than the sum of its proper divisors (495475).

6440993 is a wasteful number, since it uses less digits than its factorization.

6440993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 495474.

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

The square root of 6440993 is about 2537.9111489570. The cubic root of 6440993 is about 186.0591113622.

The spelling of 6440993 in words is "six million, four hundred forty thousand, nine hundred ninety-three".