81445587697 has 2 divisors, whose sum is σ = 81445587698. Its totient is φ = 81445587696.

The previous prime is 81445587679. The next prime is 81445587749. The reversal of 81445587697 is 79678554418.

Together with previous prime (81445587679) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73519068736 + 7926518961 = 271144^2 + 89031^2 .

It is a cyclic number.

It is not a de Polignac number, because 81445587697 - 2¹⁹ = 81445063409 is a prime.

It is not a weakly prime, because it can be changed into another prime (81445587617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40722793848 + 40722793849.

It is an arithmetic number, because the mean of its divisors is an integer number (40722793849).

Almost surely, 2^81445587697 is an apocalyptic number.

It is an amenable number.

81445587697 is a deficient number, since it is larger than the sum of its proper divisors (1).

81445587697 is an equidigital number, since it uses as much as digits as its factorization.

81445587697 is an evil number, because the sum of its binary digits is even.

The product of its digits is 67737600, while the sum is 64.

The spelling of 81445587697 in words is "eighty-one billion, four hundred forty-five million, five hundred eighty-seven thousand, six hundred ninety-seven".