78644044681 has 2 divisors, whose sum is σ = 78644044682. Its totient is φ = 78644044680.

The previous prime is 78644044679. The next prime is 78644044741. The reversal of 78644044681 is 18644044687.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78563044681 + 81000000 = 280291^2 + 9000^2 .

It is a cyclic number.

It is not a de Polignac number, because 78644044681 - 2¹ = 78644044679 is a prime.

It is a super-2 number, since 2×78644044681² (a number of 23 digits) contains 22 as substring.

Together with 78644044679, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (78644024681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39322022340 + 39322022341.

It is an arithmetic number, because the mean of its divisors is an integer number (39322022341).

Almost surely, 2^78644044681 is an apocalyptic number.

It is an amenable number.

78644044681 is a deficient number, since it is larger than the sum of its proper divisors (1).

78644044681 is an equidigital number, since it uses as much as digits as its factorization.

78644044681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4128768, while the sum is 52.

The spelling of 78644044681 in words is "seventy-eight billion, six hundred forty-four million, forty-four thousand, six hundred eighty-one".