65817763781 has 18 divisors (see below), whose sum is σ = 84156605190. Its totient is φ = 51286564560.

The previous prime is 65817763763. The next prime is 65817763793. The reversal of 65817763781 is 18736771856.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 50449202881 + 15368560900 = 224609^2 + 123970^2 .

It is not a de Polignac number, because 65817763781 - 2⁶ = 65817763717 is a prime.

It is a super-2 number, since 2×65817763781² (a number of 22 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 65817763781.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65817763741) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 5544566 + ... + 5556423.

It is an arithmetic number, because the mean of its divisors is an integer number (4675366955).

Almost surely, 2^65817763781 is an apocalyptic number.

It is an amenable number.

65817763781 is a deficient number, since it is larger than the sum of its proper divisors (18338841409).

65817763781 is a wasteful number, since it uses less digits than its factorization.

65817763781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11101025 (or 11101007 counting only the distinct ones).

The product of its digits is 11854080, while the sum is 59.

The spelling of 65817763781 in words is "sixty-five billion, eight hundred seventeen million, seven hundred sixty-three thousand, seven hundred eighty-one".