6658105721 has 2 divisors, whose sum is σ = 6658105722. Its totient is φ = 6658105720.

The previous prime is 6658105687. The next prime is 6658105747. The reversal of 6658105721 is 1275018566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3401805625 + 3256300096 = 58325^2 + 57064^2 .

It is a cyclic number.

It is not a de Polignac number, because 6658105721 - 2¹⁴ = 6658089337 is a prime.

It is not a weakly prime, because it can be changed into another prime (6658105921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3329052860 + 3329052861.

It is an arithmetic number, because the mean of its divisors is an integer number (3329052861).

Almost surely, 2^6658105721 is an apocalyptic number.

It is an amenable number.

6658105721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6658105721 is an equidigital number, since it uses as much as digits as its factorization.

6658105721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 100800, while the sum is 41.

The square root of 6658105721 is about 81597.2163802173. The cubic root of 6658105721 is about 1881.2660968428.

The spelling of 6658105721 in words is "six billion, six hundred fifty-eight million, one hundred five thousand, seven hundred twenty-one".