78809894369 has 2 divisors, whose sum is σ = 78809894370. Its totient is φ = 78809894368.

The previous prime is 78809894351. The next prime is 78809894377. The reversal of 78809894369 is 96349890887.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54765360400 + 24044533969 = 234020^2 + 155063^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78809894369 is a prime.

It is a super-2 number, since 2×78809894369² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78809894389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39404947184 + 39404947185.

It is an arithmetic number, because the mean of its divisors is an integer number (39404947185).

Almost surely, 2^78809894369 is an apocalyptic number.

It is an amenable number.

78809894369 is a deficient number, since it is larger than the sum of its proper divisors (1).

78809894369 is an equidigital number, since it uses as much as digits as its factorization.

78809894369 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 188116992, while the sum is 71.

The spelling of 78809894369 in words is "seventy-eight billion, eight hundred nine million, eight hundred ninety-four thousand, three hundred sixty-nine".