65720321 has 2 divisors, whose sum is σ = 65720322. Its totient is φ = 65720320.

The previous prime is 65720299. The next prime is 65720323. The reversal of 65720321 is 12302756.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53217025 + 12503296 = 7295^2 + 3536^2 .

It is a cyclic number.

It is not a de Polignac number, because 65720321 - 2⁶ = 65720257 is a prime.

It is a Sophie Germain prime.

Together with 65720323, 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 (65720323) 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, 32860160 + 32860161.

It is an arithmetic number, because the mean of its divisors is an integer number (32860161).

Almost surely, 2^65720321 is an apocalyptic number.

It is an amenable number.

65720321 is a deficient number, since it is larger than the sum of its proper divisors (1).

65720321 is an equidigital number, since it uses as much as digits as its factorization.

65720321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2520, while the sum is 26.

The square root of 65720321 is about 8106.8070780055. The cubic root of 65720321 is about 403.5523605280.

The spelling of 65720321 in words is "sixty-five million, seven hundred twenty thousand, three hundred twenty-one".