6420643 has 4 divisors (see below), whose sum is σ = 6426160. Its totient is φ = 6415128.

The previous prime is 6420599. The next prime is 6420683. The reversal of 6420643 is 3460246.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6420643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6420683) 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, 255 + ... + 3592.

It is an arithmetic number, because the mean of its divisors is an integer number (1606540).

Almost surely, 2^6420643 is an apocalyptic number.

6420643 is a deficient number, since it is larger than the sum of its proper divisors (5517).

6420643 is a wasteful number, since it uses less digits than its factorization.

6420643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5516.

The product of its (nonzero) digits is 3456, while the sum is 25.

The square root of 6420643 is about 2533.8987746159. The cubic root of 6420643 is about 185.8629564382.

Adding to 6420643 its reverse (3460246), we get a palindrome (9880889).

The spelling of 6420643 in words is "six million, four hundred twenty thousand, six hundred forty-three".