6687649 has 4 divisors (see below), whose sum is σ = 6694164. Its totient is φ = 6681136.

The previous prime is 6687631. The next prime is 6687689. The reversal of 6687649 is 9467866.

6687649 = T₂₁₁₀ + T₂₁₁₁ + T₂₁₁₂.

6687649 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5107600 + 1580049 = 2260^2 + 1257^2 .

It is a cyclic number.

It is not a de Polignac number, because 6687649 - 2⁵ = 6687617 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6687599 and 6687608.

It is not an unprimeable number, because it can be changed into a prime (6687689) 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, 1342 + ... + 3895.

It is an arithmetic number, because the mean of its divisors is an integer number (1673541).

Almost surely, 2^6687649 is an apocalyptic number.

6687649 is the 2112-nd centered triangular number.

It is an amenable number.

6687649 is a deficient number, since it is larger than the sum of its proper divisors (6515).

6687649 is a wasteful number, since it uses less digits than its factorization.

6687649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6514.

The product of its digits is 435456, while the sum is 46.

The square root of 6687649 is about 2586.0489167841. The cubic root of 6687649 is about 188.4044503046.

The spelling of 6687649 in words is "six million, six hundred eighty-seven thousand, six hundred forty-nine".