6649639 has 4 divisors (see below), whose sum is σ = 6999640. Its totient is φ = 6299640.

The previous prime is 6649633. The next prime is 6649661. The reversal of 6649639 is 9369466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9369466 = 2 ⋅4684733.

It is not a de Polignac number, because 6649639 - 2³ = 6649631 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6649595 and 6649604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6649631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 174972 + ... + 175009.

It is an arithmetic number, because the mean of its divisors is an integer number (1749910).

Almost surely, 2^6649639 is an apocalyptic number.

6649639 is a deficient number, since it is larger than the sum of its proper divisors (350001).

6649639 is a wasteful number, since it uses less digits than its factorization.

6649639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350000.

The product of its digits is 209952, while the sum is 43.

The square root of 6649639 is about 2578.6893957978. The cubic root of 6649639 is about 188.0468326814.

The spelling of 6649639 in words is "six million, six hundred forty-nine thousand, six hundred thirty-nine".