6628921 has 8 divisors (see below), whose sum is σ = 7313544. Its totient is φ = 5969280.

The previous prime is 6628879. The next prime is 6628943. The reversal of 6628921 is 1298266.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 921600 + 5707321 = 960^2 + 2389^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6628921 - 2⁹ = 6628409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6628981) 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 7 ways as a sum of consecutive naturals, for example, 5686 + ... + 6751.

It is an arithmetic number, because the mean of its divisors is an integer number (914193).

Almost surely, 2^6628921 is an apocalyptic number.

It is an amenable number.

6628921 is a deficient number, since it is larger than the sum of its proper divisors (684623).

6628921 is a wasteful number, since it uses less digits than its factorization.

6628921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12491.

The product of its digits is 10368, while the sum is 34.

The square root of 6628921 is about 2574.6691049531. The cubic root of 6628921 is about 187.8513329733.

The spelling of 6628921 in words is "six million, six hundred twenty-eight thousand, nine hundred twenty-one".