64703767781 has 2 divisors, whose sum is σ = 64703767782. Its totient is φ = 64703767780.

The previous prime is 64703767753. The next prime is 64703767879. The reversal of 64703767781 is 18776730746.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42343350625 + 22360417156 = 205775^2 + 149534^2 .

It is a cyclic number.

It is not a de Polignac number, because 64703767781 - 2¹⁸ = 64703505637 is a prime.

It is a super-2 number, since 2×64703767781² (a number of 22 digits) 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 (64703767081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32351883890 + 32351883891.

It is an arithmetic number, because the mean of its divisors is an integer number (32351883891).

Almost surely, 2^64703767781 is an apocalyptic number.

It is an amenable number.

64703767781 is a deficient number, since it is larger than the sum of its proper divisors (1).

64703767781 is an equidigital number, since it uses as much as digits as its factorization.

64703767781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8297856, while the sum is 56.

The spelling of 64703767781 in words is "sixty-four billion, seven hundred three million, seven hundred sixty-seven thousand, seven hundred eighty-one".