6621664 has 72 divisors (see below), whose sum is σ = 15685488. Its totient is φ = 2741760.

The previous prime is 6621649. The next prime is 6621691. The reversal of 6621664 is 4661266.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 64237 + ... + 64339.

It is an arithmetic number, because the mean of its divisors is an integer number (217854).

Almost surely, 2^6621664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6621664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7842744).

6621664 is an abundant number, since it is smaller than the sum of its proper divisors (9063824).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6621664 is a wasteful number, since it uses less digits than its factorization.

6621664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168 (or 153 counting only the distinct ones).

The product of its digits is 10368, while the sum is 31.

The square root of 6621664 is about 2573.2594117189. The cubic root of 6621664 is about 187.7827579672.

The spelling of 6621664 in words is "six million, six hundred twenty-one thousand, six hundred sixty-four".