6687221 has 4 divisors (see below), whose sum is σ = 7039200. Its totient is φ = 6335244.

The previous prime is 6687209. The next prime is 6687229. The reversal of 6687221 is 1227866.

6687221 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 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 6687221 - 2¹⁴ = 6670837 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6687229) 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, 175961 + ... + 175998.

It is an arithmetic number, because the mean of its divisors is an integer number (1759800).

Almost surely, 2^6687221 is an apocalyptic number.

It is an amenable number.

6687221 is a deficient number, since it is larger than the sum of its proper divisors (351979).

6687221 is a wasteful number, since it uses less digits than its factorization.

6687221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 351978.

The product of its digits is 8064, while the sum is 32.

The square root of 6687221 is about 2585.9661637384. The cubic root of 6687221 is about 188.4004310134.

The spelling of 6687221 in words is "six million, six hundred eighty-seven thousand, two hundred twenty-one".