66299921 has 2 divisors, whose sum is σ = 66299922. Its totient is φ = 66299920.

The previous prime is 66299903. The next prime is 66299923. The reversal of 66299921 is 12999266.

66299921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 34939921 + 31360000 = 5911^2 + 5600^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66299921 is a prime.

It is a Sophie Germain prime.

Together with 66299923, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (66299923) 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, 33149960 + 33149961.

It is an arithmetic number, because the mean of its divisors is an integer number (33149961).

Almost surely, 2^66299921 is an apocalyptic number.

It is an amenable number.

66299921 is a deficient number, since it is larger than the sum of its proper divisors (1).

66299921 is an equidigital number, since it uses as much as digits as its factorization.

66299921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 104976, while the sum is 44.

The square root of 66299921 is about 8142.4763432263. The cubic root of 66299921 is about 404.7352249962.

The spelling of 66299921 in words is "sixty-six million, two hundred ninety-nine thousand, nine hundred twenty-one".