6642257721 has 16 divisors (see below), whose sum is σ = 9731994048. Its totient is φ = 3996224000.

The previous prime is 6642257711. The next prime is 6642257813. The reversal of 6642257721 is 1277522466.

It is a cyclic number.

It is not a de Polignac number, because 6642257721 - 2⁷ = 6642257593 is a prime.

It is a super-2 number, since 2×6642257721² = 88239175264368227682, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6642257711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 730080 + ... + 739121.

It is an arithmetic number, because the mean of its divisors is an integer number (608249628).

Almost surely, 2^6642257721 is an apocalyptic number.

It is an amenable number.

6642257721 is a deficient number, since it is larger than the sum of its proper divisors (3089736327).

6642257721 is a wasteful number, since it uses less digits than its factorization.

6642257721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1469352.

The product of its digits is 282240, while the sum is 42.

The square root of 6642257721 is about 81500.0473680844. The cubic root of 6642257721 is about 1879.7722789855.

The spelling of 6642257721 in words is "six billion, six hundred forty-two million, two hundred fifty-seven thousand, seven hundred twenty-one".