6621665 has 8 divisors (see below), whose sum is σ = 7960680. Its totient is φ = 5287552.

The previous prime is 6621649. The next prime is 6621691. The reversal of 6621665 is 5661266.

It can be written as a sum of positive squares in 4 ways, for example, as 351649 + 6270016 = 593^2 + 2504^2 .

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 6621665 - 2⁴ = 6621649 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3227 + ... + 4863.

It is an arithmetic number, because the mean of its divisors is an integer number (995085).

Almost surely, 2^6621665 is an apocalyptic number.

It is an amenable number.

6621665 is a deficient number, since it is larger than the sum of its proper divisors (1339015).

6621665 is a wasteful number, since it uses less digits than its factorization.

6621665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2451.

The product of its digits is 12960, while the sum is 32.

The square root of 6621665 is about 2573.2596060250. The cubic root of 6621665 is about 187.7827674202.

The spelling of 6621665 in words is "six million, six hundred twenty-one thousand, six hundred sixty-five".