6643749 has 16 divisors (see below), whose sum is σ = 10657280. Its totient is φ = 3596400.

The previous prime is 6643739. The next prime is 6643781. The reversal of 6643749 is 9473466.

It is not a de Polignac number, because 6643749 - 2⁴ = 6643733 is a prime.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a d-powerful number, because it can be written as 6⁴ + 6⁸ + 4³ + 3¹¹ + 7⁴ + 4⁴ + 9⁷ .

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6643729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7927 + ... + 8724.

It is an arithmetic number, because the mean of its divisors is an integer number (666080).

Almost surely, 2^6643749 is an apocalyptic number.

It is an amenable number.

6643749 is a deficient number, since it is larger than the sum of its proper divisors (4013531).

6643749 is a wasteful number, since it uses less digits than its factorization.

6643749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16680.

The product of its digits is 108864, while the sum is 39.

The square root of 6643749 is about 2577.5470897735. The cubic root of 6643749 is about 187.9912946776.

The spelling of 6643749 in words is "six million, six hundred forty-three thousand, seven hundred forty-nine".