65648641781 has 2 divisors, whose sum is σ = 65648641782. Its totient is φ = 65648641780.

The previous prime is 65648641777. The next prime is 65648641783. The reversal of 65648641781 is 18714684656.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61421691556 + 4226950225 = 247834^2 + 65015^2 .

It is a cyclic number.

It is not a de Polignac number, because 65648641781 - 2² = 65648641777 is a prime.

It is a super-2 number, since 2×65648641781² (a number of 22 digits) contains 22 as substring.

Together with 65648641783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (65648641783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32824320890 + 32824320891.

It is an arithmetic number, because the mean of its divisors is an integer number (32824320891).

Almost surely, 2^65648641781 is an apocalyptic number.

It is an amenable number.

65648641781 is a deficient number, since it is larger than the sum of its proper divisors (1).

65648641781 is an equidigital number, since it uses as much as digits as its factorization.

65648641781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7741440, while the sum is 56.

The spelling of 65648641781 in words is "sixty-five billion, six hundred forty-eight million, six hundred forty-one thousand, seven hundred eighty-one".