64993824781 has 2 divisors, whose sum is σ = 64993824782. Its totient is φ = 64993824780.

The previous prime is 64993824773. The next prime is 64993824803. The reversal of 64993824781 is 18742839946.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64571892100 + 421932681 = 254110^2 + 20541^2 .

It is a cyclic number.

It is not a de Polignac number, because 64993824781 - 2³ = 64993824773 is a prime.

It is a super-2 number, since 2×64993824781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (64993822781) 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, 32496912390 + 32496912391.

It is an arithmetic number, because the mean of its divisors is an integer number (32496912391).

Almost surely, 2^64993824781 is an apocalyptic number.

It is an amenable number.

64993824781 is a deficient number, since it is larger than the sum of its proper divisors (1).

64993824781 is an equidigital number, since it uses as much as digits as its factorization.

64993824781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20901888, while the sum is 61.

The spelling of 64993824781 in words is "sixty-four billion, nine hundred ninety-three million, eight hundred twenty-four thousand, seven hundred eighty-one".