6440605643 has 4 divisors (see below), whose sum is σ = 6441255360. Its totient is φ = 6439955928.

The previous prime is 6440605627. The next prime is 6440605649. The reversal of 6440605643 is 3465060446.

It is a happy number.

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 6440605643 - 2⁴ = 6440605627 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6440605597 and 6440605606.

It is not an unprimeable number, because it can be changed into a prime (6440605649) 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, 309755 + ... + 329892.

It is an arithmetic number, because the mean of its divisors is an integer number (1610313840).

Almost surely, 2^6440605643 is an apocalyptic number.

6440605643 is a deficient number, since it is larger than the sum of its proper divisors (649717).

6440605643 is a wasteful number, since it uses less digits than its factorization.

6440605643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 649716.

The product of its (nonzero) digits is 207360, while the sum is 38.

The square root of 6440605643 is about 80253.3839971873. The cubic root of 6440605643 is about 1860.5538146399.

The spelling of 6440605643 in words is "six billion, four hundred forty million, six hundred five thousand, six hundred forty-three".