6643978 has 8 divisors (see below), whose sum is σ = 10872000. Its totient is φ = 3019980.

The previous prime is 6643969. The next prime is 6643981. The reversal of 6643978 is 8793466.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 150978 + ... + 151021.

It is an arithmetic number, because the mean of its divisors is an integer number (1359000).

Almost surely, 2^6643978 is an apocalyptic number.

6643978 is a deficient number, since it is larger than the sum of its proper divisors (4228022).

6643978 is a wasteful number, since it uses less digits than its factorization.

6643978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 302012.

The product of its digits is 217728, while the sum is 43.

The square root of 6643978 is about 2577.5915114696. The cubic root of 6643978 is about 187.9934545782.

It can be divided in two parts, 66 and 43978, that added together give a palindrome (44044).

The spelling of 6643978 in words is "six million, six hundred forty-three thousand, nine hundred seventy-eight".