6544392721 has 2 divisors, whose sum is σ = 6544392722. Its totient is φ = 6544392720.

The previous prime is 6544392719. The next prime is 6544392727. The reversal of 6544392721 is 1272934456.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6470432721 + 73960000 = 80439^2 + 8600^2 .

It is a cyclic number.

It is not a de Polignac number, because 6544392721 - 2¹ = 6544392719 is a prime.

Together with 6544392719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (6544392727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3272196360 + 3272196361.

It is an arithmetic number, because the mean of its divisors is an integer number (3272196361).

Almost surely, 2^6544392721 is an apocalyptic number.

It is an amenable number.

6544392721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6544392721 is an equidigital number, since it uses as much as digits as its factorization.

6544392721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 43.

The square root of 6544392721 is about 80897.4209786690. The cubic root of 6544392721 is about 1870.4945664918.

The spelling of 6544392721 in words is "six billion, five hundred forty-four million, three hundred ninety-two thousand, seven hundred twenty-one".