81910793149 has 2 divisors, whose sum is σ = 81910793150. Its totient is φ = 81910793148.

The previous prime is 81910793147. The next prime is 81910793197. The reversal of 81910793149 is 94139701918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81755964900 + 154828249 = 285930^2 + 12443^2 .

It is a cyclic number.

It is not a de Polignac number, because 81910793149 - 2¹ = 81910793147 is a prime.

It is a super-4 number, since 4×81910793149⁴ (a number of 45 digits) contains 4444 as substring.

Together with 81910793147, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 81910793096 and 81910793105.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81910793147) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40955396574 + 40955396575.

It is an arithmetic number, because the mean of its divisors is an integer number (40955396575).

Almost surely, 2^81910793149 is an apocalyptic number.

It is an amenable number.

81910793149 is a deficient number, since it is larger than the sum of its proper divisors (1).

81910793149 is an equidigital number, since it uses as much as digits as its factorization.

81910793149 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 489888, while the sum is 52.

The spelling of 81910793149 in words is "eighty-one billion, nine hundred ten million, seven hundred ninety-three thousand, one hundred forty-nine".