66301721 has 2 divisors, whose sum is σ = 66301722. Its totient is φ = 66301720.

The previous prime is 66301699. The next prime is 66301723. The reversal of 66301721 is 12710366.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61011721 + 5290000 = 7811^2 + 2300^2 .

It is a cyclic number.

It is not a de Polignac number, because 66301721 - 2¹⁴ = 66285337 is a prime.

Together with 66301723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66301723) 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, 33150860 + 33150861.

It is an arithmetic number, because the mean of its divisors is an integer number (33150861).

Almost surely, 2^66301721 is an apocalyptic number.

It is an amenable number.

66301721 is a deficient number, since it is larger than the sum of its proper divisors (1).

66301721 is an equidigital number, since it uses as much as digits as its factorization.

66301721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 66301721 is about 8142.5868739609. The cubic root of 66301721 is about 404.7388877296.

The spelling of 66301721 in words is "sixty-six million, three hundred one thousand, seven hundred twenty-one".