81756511049 has 2 divisors, whose sum is σ = 81756511050. Its totient is φ = 81756511048.

The previous prime is 81756511037. The next prime is 81756511069. The reversal of 81756511049 is 94011565718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 66313975225 + 15442535824 = 257515^2 + 124268^2 .

It is a cyclic number.

It is not a de Polignac number, because 81756511049 - 2⁴ = 81756511033 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81756510994 and 81756511012.

It is not a weakly prime, because it can be changed into another prime (81756511069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40878255524 + 40878255525.

It is an arithmetic number, because the mean of its divisors is an integer number (40878255525).

Almost surely, 2^81756511049 is an apocalyptic number.

It is an amenable number.

81756511049 is a deficient number, since it is larger than the sum of its proper divisors (1).

81756511049 is an equidigital number, since it uses as much as digits as its factorization.

81756511049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 302400, while the sum is 47.

The spelling of 81756511049 in words is "eighty-one billion, seven hundred fifty-six million, five hundred eleven thousand, forty-nine".