6605721 has 24 divisors (see below), whose sum is σ = 9959040. Its totient is φ = 4215456.

The previous prime is 6605717. The next prime is 6605737. The reversal of 6605721 is 1275066.

It is not a de Polignac number, because 6605721 - 2² = 6605717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6605701) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 27520 + ... + 27758.

It is an arithmetic number, because the mean of its divisors is an integer number (414960).

Almost surely, 2^6605721 is an apocalyptic number.

It is an amenable number.

6605721 is a deficient number, since it is larger than the sum of its proper divisors (3353319).

6605721 is a wasteful number, since it uses less digits than its factorization.

6605721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365 (or 362 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 6605721 is about 2570.1597226632. The cubic root of 6605721 is about 187.6319284842.

The spelling of 6605721 in words is "six million, six hundred five thousand, seven hundred twenty-one".