6639949 has 4 divisors (see below), whose sum is σ = 6989440. Its totient is φ = 6290460.

The previous prime is 6639943. The next prime is 6639989. The reversal of 6639949 is 9499366.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6639949 - 2¹⁹ = 6115661 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6639899 and 6639908.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6639943) by changing a digit.

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, 174717 + ... + 174754.

It is an arithmetic number, because the mean of its divisors is an integer number (1747360).

Almost surely, 2^6639949 is an apocalyptic number.

It is an amenable number.

6639949 is a deficient number, since it is larger than the sum of its proper divisors (349491).

6639949 is a wasteful number, since it uses less digits than its factorization.

6639949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349490.

The product of its digits is 314928, while the sum is 46.

The square root of 6639949 is about 2576.8098494068. The cubic root of 6639949 is about 187.9554462854.

The spelling of 6639949 in words is "six million, six hundred thirty-nine thousand, nine hundred forty-nine".