81445587749 has 2 divisors, whose sum is σ = 81445587750. Its totient is φ = 81445587748.

The previous prime is 81445587697. The next prime is 81445587761. The reversal of 81445587749 is 94778554418.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81356152900 + 89434849 = 285230^2 + 9457^2 .

It is a cyclic number.

It is not a de Polignac number, because 81445587749 - 2⁸ = 81445587493 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81445587691 and 81445587700.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81445587779) 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, 40722793874 + 40722793875.

It is an arithmetic number, because the mean of its divisors is an integer number (40722793875).

Almost surely, 2^81445587749 is an apocalyptic number.

It is an amenable number.

81445587749 is a deficient number, since it is larger than the sum of its proper divisors (1).

81445587749 is an equidigital number, since it uses as much as digits as its factorization.

81445587749 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45158400, while the sum is 62.

The spelling of 81445587749 in words is "eighty-one billion, four hundred forty-five million, five hundred eighty-seven thousand, seven hundred forty-nine".