81078741643849 has 2 divisors, whose sum is σ = 81078741643850. Its totient is φ = 81078741643848.

The previous prime is 81078741643777. The next prime is 81078741643871. The reversal of 81078741643849 is 94834614787018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78968869192249 + 2109872451600 = 8886443^2 + 1452540^2 .

It is a cyclic number.

It is not a de Polignac number, because 81078741643849 - 2⁹ = 81078741643337 is a prime.

It is not a weakly prime, because it can be changed into another prime (81078741646849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40539370821924 + 40539370821925.

It is an arithmetic number, because the mean of its divisors is an integer number (40539370821925).

Almost surely, 2^{81078741643849} is an apocalyptic number.

It is an amenable number.

81078741643849 is a deficient number, since it is larger than the sum of its proper divisors (1).

81078741643849 is an equidigital number, since it uses as much as digits as its factorization.

81078741643849 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 260112384, while the sum is 70.

The spelling of 81078741643849 in words is "eighty-one trillion, seventy-eight billion, seven hundred forty-one million, six hundred forty-three thousand, eight hundred forty-nine".