78397561889 has 2 divisors, whose sum is σ = 78397561890. Its totient is φ = 78397561888.

The previous prime is 78397561877. The next prime is 78397561897. The reversal of 78397561889 is 98816579387.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76853700625 + 1543861264 = 277225^2 + 39292^2 .

It is an emirp because it is prime and its reverse (98816579387) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78397561889 - 2³² = 74102594593 is a prime.

It is a super-2 number, since 2×78397561889² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78397567889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39198780944 + 39198780945.

It is an arithmetic number, because the mean of its divisors is an integer number (39198780945).

Almost surely, 2^78397561889 is an apocalyptic number.

It is an amenable number.

78397561889 is a deficient number, since it is larger than the sum of its proper divisors (1).

78397561889 is an equidigital number, since it uses as much as digits as its factorization.

78397561889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 182891520, while the sum is 71.

The spelling of 78397561889 in words is "seventy-eight billion, three hundred ninety-seven million, five hundred sixty-one thousand, eight hundred eighty-nine".