81816838447 has 2 divisors, whose sum is σ = 81816838448. Its totient is φ = 81816838446.

The previous prime is 81816838399. The next prime is 81816838469. The reversal of 81816838447 is 74483861818.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81816838447 - 2¹¹ = 81816836399 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81816838391 and 81816838400.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81816838487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40908419223 + 40908419224.

It is an arithmetic number, because the mean of its divisors is an integer number (40908419224).

Almost surely, 2^81816838447 is an apocalyptic number.

81816838447 is a deficient number, since it is larger than the sum of its proper divisors (1).

81816838447 is an equidigital number, since it uses as much as digits as its factorization.

81816838447 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8257536, while the sum is 58.

The spelling of 81816838447 in words is "eighty-one billion, eight hundred sixteen million, eight hundred thirty-eight thousand, four hundred forty-seven".