81347957849 has 2 divisors, whose sum is σ = 81347957850. Its totient is φ = 81347957848.

The previous prime is 81347957809. The next prime is 81347957857. The reversal of 81347957849 is 94875974318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73201090249 + 8146867600 = 270557^2 + 90260^2 .

It is a cyclic number.

It is not a de Polignac number, because 81347957849 - 2³⁶ = 12628481113 is a prime.

It is not a weakly prime, because it can be changed into another prime (81347957809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40673978924 + 40673978925.

It is an arithmetic number, because the mean of its divisors is an integer number (40673978925).

Almost surely, 2^81347957849 is an apocalyptic number.

It is an amenable number.

81347957849 is a deficient number, since it is larger than the sum of its proper divisors (1).

81347957849 is an equidigital number, since it uses as much as digits as its factorization.

81347957849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60963840, while the sum is 65.

The spelling of 81347957849 in words is "eighty-one billion, three hundred forty-seven million, nine hundred fifty-seven thousand, eight hundred forty-nine".