6601721 has 16 divisors (see below), whose sum is σ = 8112000. Its totient is φ = 5355504.

The previous prime is 6601717. The next prime is 6601739. The reversal of 6601721 is 1271066.

It is not a de Polignac number, because 6601721 - 2² = 6601717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6601781) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6011 + ... + 7023.

It is an arithmetic number, because the mean of its divisors is an integer number (507000).

Almost surely, 2^6601721 is an apocalyptic number.

It is an amenable number.

6601721 is a deficient number, since it is larger than the sum of its proper divisors (1510279).

6601721 is a wasteful number, since it uses less digits than its factorization.

6601721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1053 (or 1039 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 23.

The square root of 6601721 is about 2569.3814430715. The cubic root of 6601721 is about 187.5940482258.

Adding to 6601721 its reverse (1271066), we get a palindrome (7872787).

The spelling of 6601721 in words is "six million, six hundred one thousand, seven hundred twenty-one".