65781691 has 2 divisors, whose sum is σ = 65781692. Its totient is φ = 65781690.

The previous prime is 65781647. The next prime is 65781697. The reversal of 65781691 is 19618756.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-65781691 is a prime.

It is not a weakly prime, because it can be changed into another prime (65781697) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32890845 + 32890846.

It is an arithmetic number, because the mean of its divisors is an integer number (32890846).

Almost surely, 2^65781691 is an apocalyptic number.

65781691 is a deficient number, since it is larger than the sum of its proper divisors (1).

65781691 is an equidigital number, since it uses as much as digits as its factorization.

65781691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 43.

The square root of 65781691 is about 8110.5912854736. The cubic root of 65781691 is about 403.6779345925.

The spelling of 65781691 in words is "sixty-five million, seven hundred eighty-one thousand, six hundred ninety-one".