78841681 has 2 divisors, whose sum is σ = 78841682. Its totient is φ = 78841680.

The previous prime is 78841673. The next prime is 78841739. The reversal of 78841681 is 18614887.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 75968656 + 2873025 = 8716^2 + 1695^2 .

It is an emirp because it is prime and its reverse (18614887) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78841681 - 2³ = 78841673 is a prime.

It is a super-2 number, since 2×78841681² = 12432021325811522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78841181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39420840 + 39420841.

It is an arithmetic number, because the mean of its divisors is an integer number (39420841).

Almost surely, 2^78841681 is an apocalyptic number.

It is an amenable number.

78841681 is a deficient number, since it is larger than the sum of its proper divisors (1).

78841681 is an equidigital number, since it uses as much as digits as its factorization.

78841681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 86016, while the sum is 43.

The square root of 78841681 is about 8879.2838112091. The cubic root of 78841681 is about 428.7972174423.

The spelling of 78841681 in words is "seventy-eight million, eight hundred forty-one thousand, six hundred eighty-one".