65723981 has 2 divisors, whose sum is σ = 65723982. Its totient is φ = 65723980.

The previous prime is 65723939. The next prime is 65724013. The reversal of 65723981 is 18932756.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61763881 + 3960100 = 7859^2 + 1990^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-65723981 is a prime.

It is a super-2 number, since 2×65723981² = 8639283356976722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (65723881) 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, 32861990 + 32861991.

It is an arithmetic number, because the mean of its divisors is an integer number (32861991).

Almost surely, 2^65723981 is an apocalyptic number.

It is an amenable number.

65723981 is a deficient number, since it is larger than the sum of its proper divisors (1).

65723981 is an equidigital number, since it uses as much as digits as its factorization.

65723981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 41.

The square root of 65723981 is about 8107.0328110845. The cubic root of 65723981 is about 403.5598517382.

The spelling of 65723981 in words is "sixty-five million, seven hundred twenty-three thousand, nine hundred eighty-one".