6637662721 has 2 divisors, whose sum is σ = 6637662722. Its totient is φ = 6637662720.

The previous prime is 6637662701. The next prime is 6637662763. The reversal of 6637662721 is 1272667366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4447422721 + 2190240000 = 66689^2 + 46800^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6637662721 is a prime.

It is not a weakly prime, because it can be changed into another prime (6637662701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3318831360 + 3318831361.

It is an arithmetic number, because the mean of its divisors is an integer number (3318831361).

Almost surely, 2^6637662721 is an apocalyptic number.

It is an amenable number.

6637662721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6637662721 is an equidigital number, since it uses as much as digits as its factorization.

6637662721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 762048, while the sum is 46.

The square root of 6637662721 is about 81471.8523233638. The cubic root of 6637662721 is about 1879.3387142489.

The spelling of 6637662721 in words is "six billion, six hundred thirty-seven million, six hundred sixty-two thousand, seven hundred twenty-one".