81445587719 has 4 divisors (see below), whose sum is σ = 82206761544. Its totient is φ = 80684413896.

The previous prime is 81445587697. The next prime is 81445587749. The reversal of 81445587719 is 91778554418.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81445587719 is a prime.

It is a super-2 number, since 2×81445587719² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81445587749) 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 in 3 ways as a sum of consecutive naturals, for example, 380586752 + ... + 380586965.

It is an arithmetic number, because the mean of its divisors is an integer number (20551690386).

Almost surely, 2^81445587719 is an apocalyptic number.

81445587719 is a deficient number, since it is larger than the sum of its proper divisors (761173825).

81445587719 is a wasteful number, since it uses less digits than its factorization.

81445587719 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 761173824.

The product of its digits is 11289600, while the sum is 59.

The spelling of 81445587719 in words is "eighty-one billion, four hundred forty-five million, five hundred eighty-seven thousand, seven hundred nineteen".