81246440447 has 4 divisors (see below), whose sum is σ = 81784496496. Its totient is φ = 80708384400.

The previous prime is 81246440441. The next prime is 81246440507. The reversal of 81246440447 is 74404464218.

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

It is a cyclic number.

It is not a de Polignac number, because 81246440447 - 2²⁴ = 81229663231 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81246440398 and 81246440407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81246440441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 269027798 + ... + 269028099.

It is an arithmetic number, because the mean of its divisors is an integer number (20446124124).

Almost surely, 2^81246440447 is an apocalyptic number.

81246440447 is a deficient number, since it is larger than the sum of its proper divisors (538056049).

81246440447 is a wasteful number, since it uses less digits than its factorization.

81246440447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538056048.

The product of its (nonzero) digits is 688128, while the sum is 44.

The spelling of 81246440447 in words is "eighty-one billion, two hundred forty-six million, four hundred forty thousand, four hundred forty-seven".