78699397681 has 2 divisors, whose sum is σ = 78699397682. Its totient is φ = 78699397680.

The previous prime is 78699397669. The next prime is 78699397739. The reversal of 78699397681 is 18679399687.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76043026081 + 2656371600 = 275759^2 + 51540^2 .

It is a cyclic number.

It is not a de Polignac number, because 78699397681 - 2⁹ = 78699397169 is a prime.

It is a super-2 number, since 2×78699397681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78699317681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39349698840 + 39349698841.

It is an arithmetic number, because the mean of its divisors is an integer number (39349698841).

Almost surely, 2^78699397681 is an apocalyptic number.

It is an amenable number.

78699397681 is a deficient number, since it is larger than the sum of its proper divisors (1).

78699397681 is an equidigital number, since it uses as much as digits as its factorization.

78699397681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 246903552, while the sum is 73.

The spelling of 78699397681 in words is "seventy-eight billion, six hundred ninety-nine million, three hundred ninety-seven thousand, six hundred eighty-one".