6421664 has 24 divisors (see below), whose sum is σ = 12820500. Its totient is φ = 3165696.

The previous prime is 6421643. The next prime is 6421697. The reversal of 6421664 is 4661246.

It can be written as a sum of positive squares in 2 ways, for example, as 6210064 + 211600 = 2492^2 + 460^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 962 + ... + 3710.

Almost surely, 2^6421664 is an apocalyptic number.

It is an amenable number.

6421664 is a deficient number, since it is larger than the sum of its proper divisors (6398836).

6421664 is a wasteful number, since it uses less digits than its factorization.

6421664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2832 (or 2824 counting only the distinct ones).

The product of its digits is 6912, while the sum is 29.

The square root of 6421664 is about 2534.1002347974. The cubic root of 6421664 is about 185.8728077891.

The spelling of 6421664 in words is "six million, four hundred twenty-one thousand, six hundred sixty-four".