6643681 has 8 divisors (see below), whose sum is σ = 7424928. Its totient is φ = 5892000.

The previous prime is 6643667. The next prime is 6643687. The reversal of 6643681 is 1863466.

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

It is a cyclic number.

It is not a de Polignac number, because 6643681 - 2⁵ = 6643649 is a prime.

It is a super-2 number, since 2×6643681² = 88276994459522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6643687) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6915 + ... + 7816.

It is an arithmetic number, because the mean of its divisors is an integer number (928116).

Almost surely, 2^6643681 is an apocalyptic number.

It is an amenable number.

6643681 is a deficient number, since it is larger than the sum of its proper divisors (781247).

6643681 is a wasteful number, since it uses less digits than its factorization.

6643681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14783.

The product of its digits is 20736, while the sum is 34.

The square root of 6643681 is about 2577.5338989041. The cubic root of 6643681 is about 187.9906533002.

The spelling of 6643681 in words is "six million, six hundred forty-three thousand, six hundred eighty-one".