6400643 has 4 divisors (see below), whose sum is σ = 6421800. Its totient is φ = 6379488.

The previous prime is 6400637. The next prime is 6400657. The reversal of 6400643 is 3460046.

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 6400643 - 2⁴ = 6400627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6400543) 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, 10118 + ... + 10731.

It is an arithmetic number, because the mean of its divisors is an integer number (1605450).

Almost surely, 2^6400643 is an apocalyptic number.

6400643 is a deficient number, since it is larger than the sum of its proper divisors (21157).

6400643 is a wasteful number, since it uses less digits than its factorization.

6400643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21156.

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 6400643 is about 2529.9492089763. The cubic root of 6400643 is about 185.6697709313.

Adding to 6400643 its reverse (3460046), we get a palindrome (9860689).

The spelling of 6400643 in words is "six million, four hundred thousand, six hundred forty-three".